Sorry to bring up an old topic, but I'm having this exact same issue. I'm using MariaDB 10.7.3. The user I created for SmarterTrack is able to login without issue but then it says it can't find the database. I've tired using the local IP, localhost, 127.0.0.1, different database, different user, and even using root and letting root create the database. The SmarterTrack installer does create the database, but then complains it doesn't exist.
In C:\ProgramFiles (x86)\SmarterTools\SmarterTrack\MRS\App_Data\Logs\ and then in the log file, I see this when I use a valid user that can connect but allegedly cannot connect to the database:
[2022-02-21 1:37:07 PM]
Application_Start - Database is unavailable or has not been configured
I was only able to get the latest version of SmarterTrack to install on MariaDB by downgrading to MariaDB 10.5. When I did this, the installer worked perfectly. No errors.