I do not know the specific Role or Permission required. It might be in the help documentation,b ut the security folks should be able to figure it out from the error message. Someone else may know the exact Role or Roles needed.
The ID you are using does not have external access to the RFC pool, but you should also provide which RFCs you are planning to use as some have additional permissions required.
Regards, Mike
SAP Customer Experience Group - CEG