I see that you have to enable a datapack upon world creation. how would I do that on a server? And could I enable it while keeping our current progress?

To enable it, all you have to do is add ratlantis to initial-enabled-packs in the server.properties file. As far as I'm aware, you have to do this BEFORE generating a world due to how this property works.

It doesn't look like there's a way to enable the pack on existing worlds. I tried messing with the /datapack command to enable it but it doesn't seem to like that. The pack says its enabled, however the dimension doesn't work, and it gets disabled when the world restarts. If I find a different workaround I'll post it here, but for now youll have to start a new world to use ratlantis stuff