You need to have an account on this website to play on the server.
To fix the “Your client is too old for this server” message. Thanks to install the last snapshot. You can find the last snapshot here : https://mxsimulator.net/en/
To fix “client track modified”, please go on the page of the track that you are having issues with and download all necessary packs and add them on your game.
This is a short tutorial to explain you how to play on MxsRank : https://mxsrank.com/how-to-play-on-mxsrank/
You can find Mx Simulator in the best price on https://mxsimulator.net