Plays a role "in" or "at" doing something?
“In” appears to be the more common preposition used after “play a role”:
play a part/play a role
If something or someone plays a part or plays a role in a situation, they are involved in it and have an effect on it.
They played a part in the life of their community.
The U.N. would play a major role in monitoring a ceasefire.
(Collins Dictionary)
Also Google Books shows that play a role in is the more common collocation.