thats its not an teaspeak related thing.
If your friend needs help, he can just read on the first page. :)
And these you post here, has nothing to-do with premium =)
protocol_key is not "premium license" =)
The changes of "version" will only work, if you have premium. So if you change it now, it will not work.
It will first work, after you have added license to config.yml 😎 and ofcourse required to restart.
you need to import "permissions".
So you need to create a "second" teaspeakserver > login yatqa > import from serveradmin there (remember, remove maxclients permission eg)
Maybe that will help.
(If you can't do that...you will need to reinstall I guess)