It's pretty simple, just not well documented.
1. First, write down the macs of each AP, and connect them so they are both assoicated to the controller.
2. Enable Zero Touch Config on your controller
3. Goto the Security Page, under AAA on the left side, click on MAC Filtering.
4. Add a Mac Filter for each of the AP's Macs (Which you already wrote down)
5. Goto the Wireless Page. Select Detail on one of the APs. Change it from Local Mode to Bridge AP
and hit APPLY. The AP should reboot.
6. Repeat this step with the Other AP.
7. Once both AP's have rebooted, and reassoiated, and you have confirmed they are both in Bridge AP mode, you can unpluge one of them. Just apply power, and it should setup the AP bridge.
8 IMPORTANT You cannot do this from WCS (I've never seen the option there)
From the AP details screen, select Ethernet Bridging (check the checkbox) on BOTH of the bridges.
You should be able to plug a client into the RJ45 of your remote bridge, and pass traffic now.
THIS Step is only nessacary if you entend to use the ethenet interface on the remote AP.
If you continue to have problems, you can try this: (Try the above first, since I don't think you created the MAC Filter, which YOU MUST do)
From controller CLI "config network allow-old-bridge-aps enable"
