Hey @lsnesn thanks for posting about this. While we don't allow users to define custom SSH credentials on Cloud, you can add Retool's ssh userkey to your ssh host. More about that here: https://docs.retool.com/data-sources/guides/ssh-tunnels
If you're self-hosting Retool, your resource setting will look like this:
Hope this helps point you in the right direction!
Ah, it also looks like you might have connected with a teammate of mine on Retool Support over email, and it sounded like the issue might have been the connection string was slightly off, but you were able to get a sample application working?