@Alonsan 

Strange question, but in general Yes.  Do you mean physically...if so be aware that the OC200 ports are 100M only so you will limit your wireless clients max throughput.  If you mean logically then simply put the OC200 on the same IP subnet as the AP and it will find it and want to adopt it.  Be aware that you will need to rebuild any existing AP configuration within the Controller so that it gets pushed back to the AP.

I assume you have no Omada router...so a third party device will take care of DHCP and any NAT'ing.

I assume you have no OMada switch...so a third party switch (or extra ports on your router) are used to connect the 245 and ultimately the OC200

  @Alonsan 

Had you previously set up the APs?  If so, that may the issue. 

Also what firmware version are you running on the EAP245's you may need to update them?

If I were you, I would set up my network config on the controller first, then adopt the router, then connect the router to the internet and start to add the (factory defaulted) AP's to the LAN port(s) of the router.  To make sure you have things working you may want to just default 1 AP and try that first :)