Windows says the download of LibreOffice is an unsafe type of file.
What link did you use to obtain your download?
It is a restrictive practice by Microsoft. Go to Start menu - Settings -Apps - Apps and Features and under the heading Choose where to get apps change the drop down from Microsoft store only to Anywhere.
Make sure you download from libreoffice.org. When you have downloaded and anti virus scanned, turn off anti virus for the install then turn AV back on. More info on General Installation issues (Windows)
Note: if you have Windows 10S you will not be able to download from anywhere except Microsoft store. There is a one way free upgrade to Windows 10 Pro if 10S is too restrictive
Thanks for the response. In the meantime I resolved the problem by using Chrome instead of Edge. Installation went smoothly.