You are not authorized to move users to the group &1

What causes this issue?

IF &V2& = 01
You have insufficient authorization for object S_USER_GRP with ACTVT =
01.
ELSEIF &V2& = 50
You have insufficient authorization for object S_USER_GRP with ACTVT =
50.
ENDIF

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.