Never mind, I was able to figure it out!
It took me 6 days for something so simple!! I overcomplicated the whole thing because for my game I didn’t even need to use multiplayer and create a local player. I just used the Player Controller with index 0, two different Mapping Contexts, and Inputs, then I called them and checked my Player Variables if P1 = 1 or P2 = 2 to execute the movement. I’m so relieved right now.