To setup access to your site's files directly, via SFTP or SSH, you will need to login to your Indystack account. Under the site you wish to gain access to, choose the Manage option and when that page loads, from the main menu on the left, choose SFTP & SSH Access.
You will need to click the toggle option for Enable SFTP & SSL access . This is a one time option.
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.