If you're playing on PC, go get the RVGL Launcher!
When you run it it will show a screen saying The game doesn't seems to be installed. From here, you want to select Install Type: Standard (the default) and Game Preset: Online. Then click Download and Install.
After that's done, click the Packs tab and select io_cars_bonus, io_skins_bonus, and io_tracks_bonus. Then click the Install Packages button in the lower right.
Once the install is complete, you'll see various information on the Game tab. Above the Lunch RVGL button there's a Launch Parameters box. Enter the following in there:
-nointro -lobby kadalyn.rv.gl
Now go to the Repositories tab and in the input field at the bottom enter https://kadalyn.live/rvgl/schedule.json then click Add Repository.
If you're playing on Android you'll need to download and install the APK listed here.
To install it, click the completed download from your browser's notification. Android will warn you that your browser isn't allowed to install APKs and take you to the permission screen to enable it. Do so. Once installed, you may disable it again.
Run the application once, set your profile name, and close it. This will create an RVGL folder. It will attempt to create it on your SD card first, and otherwise on your main device storage. You'll have to go find this with a file manager, such as Cx File Explorer.
Now download the following additional packs:
Unzip these to the RVGL folder you found. If it asks to overwrite anything, check the "Apply to all" box and select skip (that is, don't overwrite anything!).
After you select/make a profile, go to Options then Controller Settings.
Make sure you've updated the password before joining!
If you added the repo on PC, go to the Events tab, click on my event, then click Join Kadalyn.
If you didn't use the -lobby parameter or set up the repo, you'll have to go to Start Race → Multi-Player → Join Game and then enter kadalyn.rv.gl
Once it starts up, just select Join Game.
If your connection is immediately rejected, make sure your client is up to date and you have the right packs (unmodified).
If we're playing with cars you haven't unlocked, enter CARNIVAL at the wheel screen, press enter, you'll hear a funny noise, then you can press escape to go back and change it to a real name.
Now enter your name (ideally the name you're chatting with on YouTube!) and select a car based on the day's limitations (it will say on stream).
Now select Waiting Room if you wish to play.
You'll see a list of participants. The top-most player will reiterate the limits of the day's races.
!! Please obey the same chat rules as on YouTube if you decide to chat !!
Personally I suggest using these: -nodemo -nointro -window 1920 1080
Of course, use whatever window resolution you want. Leaving it as a window will let you see YouTube chat, though!
To squeeze out some extra performance, you can use: -cubevisi -nogamma -nostars
For more options, see here.