"Fatal error" installing Osclass please help

Hello guys, I am a new user, excited about this script, but I am trying to install it in my local server without results.
I run Install, everything is ok (green checked) , fill out form for database access, submit it and after some time I get this error:

" Fatal error : Maximum execution time of 30 seconds exceeded in C:\AppServ\www\osclass\oc-includes\osclass\classes\database\DBCommandClass.php on line 955"

Please help me.
database is filled correctly

Is your database accepting local connections? Does it need “localhost” or only via ip? (127.0.0.1)
Is the database w/ port open?
Try the following to check these infos (mysql is 3306 by default):

sudo ss -tulwn

Hello xiris, thank you for your answer, I checked and:
port 3306 enabled and listening
access to DB via localhost and 127.0.0.1 work fine both.

I tried to install again today and same error, it is about maximun time for that task, any idea?
thank you