I had this issue, and here's what worked for me.

For safety reasons, I don't log in on the admin account. There is almost NEVER a reason to do this.

I'd tried running this as a Standard User - doing it this way did not give the message that I need to reboot.

I'd tried while logged in as a Standard User right clicking and "Run as Administrator." This is when I'd get the continuous You need to reboot message loop.

Finally, I logged out, signed in as Administrator, ran Quickbooks as administrator, received the message, rebooted, and then signed in AGAIN as Administrator. Ran Quickbooks and it worked!

Logged back out, tested it as standard user, and everything is working properly.