To setup access to your site's files directly, via SFTP or SSH, you will need to login to your Indystack admin panel. Go to the Sites section and click the dropdown menu option beside Manage in the site card for the site you wish to access and choose SFTP & SSH access.
Next click the toggle to turn on your SFTP & SSH access.
Once the access is setup, the page will refresh with all your SFTP and SSH access details. You cannot see the password directly, but you can copy it using the link button to the right of the password field. Then you can save it in your local application's user management by pasting it directly.