Open the Templ Panel and click on your website that you want to access the database for.
Scroll down to Database and click on the DB Admin link.
The details to login to Adminer are not needed to be entered manually. Click on the DB Admin link as shown above and then Login (as shown below) to automatically log in to Adminer and the database.
That's it. Now you should be a logged in to the database.
Related: How to connect to your database remotely (coming soon).