Your database is ok and it work just fine on a brand new Tiki 21.6 I uploaded from release package. On your server, the PHPSESSION constantly expires and this leave you with a few second to work logged as admin.
Now and it is important to consider;
- I'm not Server Admin expert (I know pretty well my way to get Tiki working 😎)
- I had only access to your Tiki tools to make such diagnostic
I loaded https://c2gk.com/tiki-phpinfo.php and compared the "SESSION" section to other Tiki I have. I believe something is wrong about the path OR the permissions of the tmp directory where are (should be) stored the sessions. Hard to say more without shell access.
I couldn't attach or upload a screenshot so...