XenForo will only become an option when vBulletin 5 is no longer supported.
The Lite version is executable, the demo version is not.
You should replace the files on your website with working ones.
I found the error.
The files in
DBTech] Advanced Post Thanks _ Like 3.0.4a8 [Demo].zip
from the website contain PHP errors.
The files in
[DBTech] Advanced Post Thanks Like (vB5) v3.0.4a8 [Lite].zip
from vbulletin.org work and do not contain PHP errors anymore.
Advanced Post Thanks Like 3.0.4a8 Demo / Lite does not work.
Files like core/packages/dbtechthanks/api/thanks/button.php give several PHP errors.
It looks like this files are generated automatically from the PRO version and contains some incomplete Pro functions.
Tested on two different PHP...