Solution:
I got it working by using event dispatchers.
I made an event dispatcher in my player pawn, which i then call in the pawn BP when i want my animation to play.
For my animated skeletal mesh i made a custom class BP (see image below), in which the the event needs to be bound to the dispatcher. The result is that the play rate in the class BP is set everytime the eventdispatcher is called in my Pawn BP.
