Meta Horizon Link Setup failing

It has downloaded about a gigabyte of installation files.
Getting to about 10-15% it stops and says "try restarting and doing setup again". 
Of course, this doesn't work. 
It started alongside the Unable-to-start-Link problems.
Also, BitDefender "detected" a bunch of items under C:\Program Files\Oculus and blocked them. 
I added C:\Program Files\Oculus and C:\Program Files\Meta Horizon\ to BitDefender exceptions. 
But lo and behold, the stupid thing won't accept restoring OVRServer exe files, it won't let anything get added to the Advanced Threat Defense exception list!