Dear Mert,
If you are sure that the connection parameters were entered correctly, which are server name, tenant name (if other than default), then check via http://localhost/#default/adminLicences whether there were ARIS licenses imported and have not expired. If you have found valid licenses, check for missing license assignments via http://localhost/#default/adminUsers on the system user's profile.
Of course, replace localhost with your ARIS server name, and in case you've created your own tenant, then replace default with your tenant name.
Cheers
Rune