is there a way to use it in multiplayer?
Wemod does not create cheats for online or multiplayer use. Single-player only.
Trainers are not for multiplayer games. No matter where on the internet you get them from.
Trainers are for offline single player games.
Technical reasons - Trainers work by injecting cheats into your PC’s RAM while a game runs from it. Multiplayer games run from a server thousands of miles away from you rather than on your PC, hence nothing in your RAM to inject into.
Moral reasons - Negatively impacting the game experience for other players is an incredibly crappy thing to do.
Legal reasons - Game developers will sue anyone who produces online cheats. (And sometimes the players who use them, if it resulted in the developer losing a fair amount of income).