You can add them by clicking the "SSH to this build" button in the "Debug via SSH" tab

[voltechs]

Is this help message still relevant? I can’t seem to find said button…

Use the same SSH public key that you use for GitHub. If you have not added your public keys to this build and you would like to SSH to it, you can add them by clicking the “SSH to this build” button in the “Debug via SSH” tab.

[tom]

Thank you for reporting this. It would make sense to remove that text.

For info this is echoed in the UI under the ‘Enable SSH step’ as the container starts: