Please go over this post:
Unfortunately, the authentication is much trickier with platform.uipath.com becoming a cloud service with better authentication.
This means that the first activity Authenticate will not work anymore. You will need to get your access_token first using the procedure from the post I liked here and then use it as you would bearer_token.
I hope it makes sense 
Anil_G
ashokkarale
Eric_Alvarado
Yoichi
Julian_Muhlbauer
SorenB
lbowen
ayumi.ouchi
lska
ppr