Hi BigBadBuddha,
The IP needs to be entered in Minecraft.
Open up Minecraft, ensure it's on the latest version (1.16.2).
Go to Multiplayer.
Click Add Server.
You can enter anything you like in the Server Name. I put "Auscraft", but that's up to you.
Then put play.auscraft.net in the "Server Address".
Click Done. Then you should see it in your server list. Double click to join.
Let me know if you have any issues.