Please read the article here carefully: https://community.arubanetworks.com/t5/Controller-Based-WLANs/Do-we-have-radio-port-redundancy-on-AP-LACP-GRE-striping-IP-and/ta-p/239920 The access point gets the LACP configuration information when it comes up in an ap-group with LACP configuration. The controller also requires an additional ip address to point the access point to.
*Since this is an AP-325, it requires high powered POE to be able to bring up the second port. Since it is also a 325, there is no power redundancy, so if one ethernet port goes down, the AP has to reboot before sending traffic through the other port. The LACP advantage is only effective in very limited circumstances on the AP-325 due to the lack of power redundancy. It is also effective in limited circumstances for additional throughput, because few WLAN setups will actually exceed 1 gigabit of actual throughput.