Install docker, grab the official docker compose file, then docker compose up -d.
Details: Look up how to install docker on elementary (I guess it’s sudo apt install docker), than you don’t have to care about the distro after that, docker works the same way everywhere. You can find countless tutorials on this, and they should work
That’s not an alternative frontend, but a different albeit very similar platform. With an alternative frontent you can see the same content, but with better and different features, usually without ads and with better privacy.