can we add "Procurement REST Service" to Custom Employee Abstract Role

Summary:

Currently we are working on incorporating Purchase Requisitions into the App using REST Services.

From the below doc, https://docs.oracle.com/en/cloud/saas/procurement/25b/oapcm/unassigned-duties.html

We found the duty Role "Procurement REST Service" can be assigned to users to access PRs through App.  Also in the doc it's mentioned that

"This duty should not be given to duty, job, or abstract roles that are assigned to end users. This duty is for application-to-application integration similar to APPID and give access to all data."

We are confused and need clarity if we can assign this role "Employee Custom Role"(abstract role) which is already assigned to all the Employees within Organization.