IKinema, that was kinda the problem. I also updated my UE version to 4.9.2 and now the “Launcher” plugin works!
However my following problem is that the character is rotated and going wierd ingame. Anyone understands why?
I noticed that when i save my rig as .wa and reopen it, the rig is also rotated, but when i move one of the helpers it gets back in the right position.
AFTER SAVE AND REOPEN .wa file: