I cannot pass the installation step 5 too but not sure it's the same case as yours or not.

In my case, it's related to the host session setting. I added the following host setting by mistake during my copy and paste action:

php_flag session.cookie_secure On

This line cause session problem at my XOOPS with http host and make MySQL login information cannot pass from dbconnection to the dbsettings page.

After remove this line from my Apache config and restart Apache service, my XOOPS installation can be continued without problem.