I've found this article (https://wiki.mikrotik.com/wiki/Connect
_ ... ss_Network) that can establish the hAP as a station, but I haven't yet figured out how to connect the Metal 52 over POE as a CPE.
First make sure your Metal is correctly setup as a CPE. Connect it directly to your computer LAN and see if you can access internet when you connect to an AP with internet.
When it is setup and working change the LAN IP from default to some other subnet like 192.168.89.0/24. You can make this change from the Quick Set page by modifying Local Network IP and the DHCP Server Range. Click "Apply" and then reboot the Metal. When it is rebooted check that you can still get internet.
Reset your hAP to factory defaults and plug the ethernet cable from the Metal into port 1 on the hAP. You should now be able to use the Metal when connected to the hAP.
If everything is working with this basic setup then make a backup on each device. Now you can experiment with other types of arrangements for the hAP such as setting it so that it is not a router.
A simple way to use port 5 POE out is to change port 5 from a slave to ether2 and then make a second bridge with ether1 and ether5 in it. You can then use ether 5 as a WAN port with POE-Out.