I just installed Premier (W10, rev 21H2) ....installer took a good 10-20 Minutes to work thru things. (should have put a stopwatch on it...I'll try to remember to do that when I install on my laptop)
The installer didn't look like it was working...i.e. blank progress bar for 4-5min
...then showed a green bar for awhile....then no green bar....then a green bar again
...then blank...then finally started up....and when I clicked the button to actually start the software...took a long time (a few minutes) again before it finally started, and I could enter the activation code.
MASSIVE patience....but if you've already terminated...don't know what partial install complications may ahve happened.