I installed it; I modified it; I repaired it (under Windows); I installed Java RE; still, LO 6.3.2 appears alone as a Win10 app.
If you can’t cope with such a problem on your own, this only means that you are not fit for alpha builds. Relax and use a stable build, don’t waste your time.
Assuming TAB is someone who wants to test the version and maybe report bugs, I could imagine a better answer.
I have no clue of Windows, but this may help https://wiki.documentfoundation.org/Installing_in_parallel/Windows
I think the better way for test different development version of LibreOffice it’s using ‘Separating Install GUI’, It is very good to download and install where you like without affect the in use version, and keeping all in the same folder. Can be found in Index of /si-gui/ for windows download and install setup.exe