The wireless interface type in pfSense is for wifi hardware in pfSense itself which is not what you have.

Your access point should simply be connected to one of the LAN ports in the 2100. Devices that connect to the AP will just get an IP from pfSense in the LAN subnet. Later you may want to move those to a new subnet so you can filter between them but I would only attempt that after first making it work as part of LAN.

The pfSense WAN should be set to PPPoE but that can only work if the upstream device is bridging the PPPoE connection correctly.