You could return the same psk for each user or group. You will also need to make a DEFAULT section as described in the meraki document https://documentation.meraki.com/MR/Encryption_and_Authentication/IPSK_with_RADIUS_Authentication to allow for unknown mac addresses. In the reply for the known users you can override the VLAN. I found a reference how to make user groups on https://stackoverflow.com/questions/71863025/freeradius-3-mac-auth-user-group-for-configuration-simplicity Good luck!
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