Just in case: At first, keep a backup of your files.
.
Alternative methods to access your files:
Does “tray” mean the default folder for your downloads?
The file you named is the installer.. (The default location of the installed program under Win 10 I already posted above.) If a direct call to the installer results in getting displayed the image you posted above, I have to give up. I installed very many versions of LibreOffice, because I tried to also have very fresh ones at hand to help a bit with bug hunting. Don’t know that screen.
And once again: I don’t know a thing like what you want to call “the bot”. The installer for LibO is by default processed as any .msi file provided by any distributor of software by a Windows program named msiexec.exe.
According to Google not many things use the phrase “Bad old password”. Ubiquiti seems to be one, maybe the .msi didn’t download fully and OS is trying to reconnect to web site to continue download but Ubiquiti WiFi needs a new password for you to access the portal to your network (and internet).
If you have Ubiquiti issue then look at their help or ask at their site.
Does “tray” mean the default folder for your downloads?
YES
The file you named is the installer.. (The default location of the installed program under Win 10 I already posted above.) If a direct call to the installer results in getting displayed the image you posted above, I have to give up.
“If a direct call to the installer…” means (I tried to open it), well, yes, I tried to open it. But I won’t give up because I have too many LO .ods and odt files that I created / edited in the past - and I need many of them in order to continue my work.
I installed very many versions of LibreOffice, because I tried to also have very fresh ones at hand to help a bit with bug hunting. Don’t know that screen.
By now, I am all too well acquainted. 
And once again: I don’t know a thing like what you want to call “the bot”. The installer for LibO is by default processed as any .msi file provided by any distributor of software by a Windows program named msiexec.exe.
Is my “bot” your LO installer? If so, so what? In that case, what next?
I can’t answer directly to this question, because both the question, and the context, that have grown in this thread, were confusing from the start, and got too confusing to this moment. But I can tell you how to restart from scratch.
Do something like this:
“When I double-click on “LibreOffice 7.5.2_win_x86-64.msi”, I see a prompt for a password. I try my old recorded password, but the message is, “Bad old password”. Here is a screenshot of my “LibreOffice 7.5.2_win_x86-64.msi”: [screenshot here]; here is the prompt for password shown when I double-click it: [screenshot from #16]; here is what it shows after I enter my recorded password: [screenshot from #15].”
Note that the missing screenshot of your “LibreOffice 7.5.2_win_x86-64.msi” would immensely help others. It could possibly show its size, the icon, and maybe allow immediately diagnose something. Note also, that the screenshots that you did provide, were cut to not show the actual website address; if you provided the browser address string, it could possibly also help understand where does your double-click send you, and maybe get an idea how it could happen initially.
“The problem started after I replaced my old computer and decided to install LibreOffice, as I had installed on my old box / after my old LibreOffice suggested me to upgrade and I tried that / after whatever else happened…”
After these things, you can optionally add stuff that you believe could help others help you, but please abstain from anything (including jokes) that do not help others help you. They just make fellow users, who have energy to read other users’ problems, and try to help, to have hard time trying to pass through debris in pursuit for information.
E.g., if you were asked “from where did you downloaded the LibreOffice 7.5.2_win_x86-64.msi”, you should provide the address and screenshots of the web page that you used to download; and best if you also tell which buttons you pressed on the page. (My suspicion is that you didn’t properly download anything, but instead, dragged a link to your downloads folder, which started all your problems; and the suggestion to re-download, that @Wanderer gave in #21, would help.)
And note how #15 does not block you - it suggests you to “Go to portal”.
Possibly the instructions for you to follow at this point would be:
This is not expected to show you any password pages, just download a file named LibreOffice_7.5.2_Win_x86-64.msi to your download folder. Its size is 342 MB, and is should look like this:
If you already have LibreOffice_7.5.2_Win_x86-64.msi in that folder, then the newly downloaded file can get a name like LibreOffice_7.5.2_Win_x86-64 (1).msi.
This is not expected to show you any password web pages (but at some point, can ask you to allow installation using admin credentials, as noted by others), but should start installation procedure, as described here. The first installer screens should look similar to this:
These items must start LibreOffice, again, without any password prompt.
If at any point in the steps 1-3, you get a password prompt like what you have shown in your screenshots, this would mean that something is really broken on your Windows system. A screencast (a video recording of your actions) could help in that case.
Kindly cease and desist; LibreOffice 7.5.2 yada yada is now installed and operational on my PC.
Earlier today, I had a keyboard problem - when I typed a single character, nothing happened. Then, I tried plugging my keyboard into all three of my USB ports to no avail. Now, for some unknown reason, my keyboard is operational, (as you see here).
FYI, maybe an hour ago, when I double clicked the LO execute file, the LO installer worked without giving me the Old Password / Create a new Password runaround. Be advised that was not the case earlier today.
In conclusion, thanks for your time, patience and advice, and please accept my apology for my snarky comments and observations. Be assured I will mind my manners if and when I visit this site again.
Dubina1
