You mentioned you’ve already had a PMS running on the machine in the past. There’s a chance that your new installation found some of the old server’s data and considers it’s still linked to your old account (btw: you could also kept using the old account to revive your server).
TL;DR:
Please open http://x.x.x.200:32400/identity (using the actual IP address of the QNAP) and check for an section/attribute claimed=„…“. Is the attribute’s value a 1 or a 0?
If it’s a 1, you’ll need to manually unlink it from the old account and reclaim it.
If you actually want to start from scratch, you might want to delete the PlexData folder mentioned in the guide above (instead of tinkering with the configuration files)
