D-Link DWL-8500AP - AirPremier AG Wireless Switching 108 Dualband Access Point Administrator's Manual page 121

NOTE: The user name and password you need to provide here is for access to the
RADIUS server, for which you will already have user accounts configured at
this point. This document does not describe how to set up Administrative
user accounts on the RADIUS server. Please consult the documentation for
your RADIUS server for these procedures.
5. Click "User Certificate" on the next page displayed.
6. Click "Yes" on the dialog displayed to install the certificate.
7. Click "Submit" to complete and click "Yes" to confirm the submittal on the popup dialog.
A Wireless Client Settings and RADIUS Server Setup
Obtaining a TLS-EAP Certificate for a Client 121