What is the relationship between the Integration System User (ISU), Integration System Security Group (ISSG),...

This question is about the correct order of Workday security assignment for integrations. Workday clearly specifies the security structure:

“You assign the ISU to the Integration System Security Group (ISSG).

Then you assign the ISSG to the domain security policies.”

This is because domain security policies apply to security groups, not directly to ISUs.

Correct Relationship Order:

Create ISU

Create/assign ISU to ISSG

Assign ISSG to the domain security policies (Get/Put/View)

That aligns exactly to option C.