Align your bus with the ghost trailer marker. Since these are "invisible," you simply back into the spot until the "attach" prompt appears.
[ETS 2 v1.36 ] Bus Mod Test | Comil Invictus Double Decker Bus BUS TERMINAL MOD ETS2 1.36
Navigate to the Cargo Market (not Freight Market) to find available passenger routes. Align your bus with the ghost trailer marker
Instead of hauling trailers, you pick up "cargo" represented as passengers. BUS TERMINAL MOD ETS2 1.36