can i play with a friend?

[ArkaiL]

where is the option of group? i wanna make the tracks with a friend and have some laugh

[Gardalice]

You can make a multiplayer session and have your friend join it, you can select if you want a career session or casual session. (you dont gain items from casual but dont lose lives)

also if you want to ride a private lobby of a bikepark you can generate the level from seed
see list of bikeparks here (https://descenders.gamepedia.com/Bike_Parks )

make sure you don't finish a run on a bikepark if you plan to session it for a while as it makes a 30 second timer appear for everyone in the lobby to hurry up and finish.