Larian Studios Forums Baldur's Gate III Baldur's Gate III - Technical & Gameplay Problems Custom Party Error - Joining failed: You're already connected ?

the tutorial could be a little clearer but the basic steps are correct and the issue is at your end not the guide... i would go back to Windows and just install the Dotnet

are you using a VPN or is the Larian launcher not running as admin for the first version of the game?... note you only need the larian launcher to be run once and it sounds like you have more than one or possibly more than a single profile