We would get this error within Power Automate Approval Flow if we are using Security Group to control access to Dynamics 365 Environment and are sending Approval to a user who is not a member of that security group.
Below is the User within the Tenant but is not member of the My CRM Group Security Group associated with that Environment.
The Security Group – My CRM Group – assigned to Environment against which flow is created.
So to fix the issue, as the error message indicates, we need to add the user to the Security group.
After adding the user to the Security Group, the flow runs successfully
Also, the User (unlicensed in our case) gets added to CRM with Approvals
User security role as shown below.
Check other posts on Approvals –
Hope it helps..