In Process builder, I have a Post to Chatter action. When this action gets triggered, I am getting error message and exception is thrown. I have attached the error line from debug logs: FLOW_ACTIONCALL_DETAIL|9086c181606dd98184557174ae5116d63ba0a-8282|myRule_1_A1|Post to Chatter|chatterPost|false|Guest users are not permitted to perform this operation.
We have gues user with the profile license 'Guest User License'.
Here is the screenshot of the Post to Chatter in Process builder: