RADIUS is a networking protocol that provides centralized Authentication, Authorization, and Accounting (AAA) management.
The question if is it possible to get the user groups or other attributes. According my understanding the answer is not but I will happy to clarify if I miss something:
During Access Request the client sends the client credentials (and optionally IP address and other parameters). A server responses with Access Accept (or Access Reject) but does not provide the user groups or other attributes.