[Cil]

Ok, so the server is currently based on 1.15.1 so make sure you're on that version. Minecraft just released a 1.15.2 so make sure you switch over to 1.15.1. to switch over versions if you don't know how, at the top left of the launcher theres a thing that says Installations. Click that. Than, if you see a version with 1.15.1 I reccomend using that. If you don't, click +New... and it will allowe you to choose a new version. You can choose a name version, but the name doesn't really matter. Click the "Version" right under the word Version (It will most likely be on 1.15.2). A pop up thing will show once you click it- Click the 1.15.1. After that, you can click the green create button in the bottom right. Don't mess with the Game Directory since I have no idea what that is o.o. Once you've clicken create, the installation will appear on your screen. you can then hover over it, and a green play button will appear. Click that, and the game will load.

If that doesn't work just tell me, I hope this guide helps