Hopefully someone with actual experience of using PCMCIA Wifi cards with Amigas can help with that. However as long as you have entered the correct MAC address in your router, I don't think you'd need to do anything special on the Amiga side.
Or, perhaps the Amiga-side driver software uses a hard-coded/random/whatever fake MAC address, not the one printed on the PCMCIA card itself???
Can you get the Amiga working if you disable MAC address filtering on your router?