While logged into your Indystack account, first make sure you are on the Sites page.

Next, for the site you want to access the database directly, click on the Manage button.

When the page loads, choose the Database access option in the main menu.

Next, click the Launch phpMyAdmin button in the main screen and that's it, your database access will load in a new tab.

Upload size is limited to 95 MB for myPhpAdmin.
For larger uploads you will need to break them into separate uploads or contact support for further assistance