@bigal_12ms 

I think I would make sure the current network plan is consistent with the future controller-owned network plan. 

Oh and Don't update any more firmware until you are done the migration!

Your easiest path is to emulate an out of the box Omada gateway-switch-AP.  So that would mean:

Management Subnet:  192.168.0.0 / 24

Management VLAN:     VLAN ID 1, untagged

Router IP:                    192.168.0.1

You then need all Omada devices on the 192.168.0.0/24 subnet, to do that typically they are connected to an upstream port which belongs to VLAN 1, and where VLAN 1 is untagged on that port.  Each of those ports can also optionally belong to one or both of VLAN 50, tagged and VLAN 100, tagged.

Once your Omada device is reachable via a 192.168.0.X address (I'm assuming your Pfsense box will hand out IP's via DHCP...you can fix/reserve them later) then you can try to adopt it.  Let's say you have an AP, it's address is 192.168.0.101 and your controller has an IP of something like 192.168.0.100 (they'll both be different I'm sure, doesn't matter).

I am assuming here that you have already ALSO defined in the controller subnets 192.168.50.0/24 and 192.168.100.0/24 which will belong to VLAN 50 and VLAN 100 respectively.

I further assume that you have created SSID50 and SSID100 and mapped them to VLAN50 and VLAN100 respectively.

I continue to assume that the port the AP is connected to is a member of VLANs 1,50,100 with its PVID set to 1

Lastly, you have create a Wifi Profile which has both SSID50 and SSID100

You should now be able to request to adopt that one AP.  You will need to provide it's current admin credentials after the initial adopt attempt fails.  Once you enter the creds, the adoption should flow through the adopt/config/provision/online steps.  You now need to ADD the Wifi Profile to this AP before it will broadcast any SSIDs.

Once the AP is broadcasting, try to attach to say SSID50.  Once authenticated, you should receive an IP from the subnet that VLAN50 is attached. 

Test for functionality.

  @bigal_12ms 

Ok, it looks like you are going forwards with your management subnet being 192.168.1.0/24. This is ok, I do run some sites on IP's other than the default subnet, but it's easier when adding or reseting devices if your default LAN is 192.168.0.0 instead of 192.168.1.0 as it is currently.

If you aren't in production, then you can change the subnet on the pfsense from 192.168.1.0 to 192.168.0.0, and force all devices to re-IP with a 192.168.0.X address....if you are production you can forge ahead with 192.168.1.X addresses.  

  @bigal_12ms 

This is where you would change it, but you will cause outages for 5-10min as everything reconverges/re-IPs.  Choose wisely :)

  @bigal_12ms 

If you don't change the Pfsense...then you need to redefine your Omada LAN to match the Pfsense...

ie below would need to change to 192.168.1.1/24

  @bigal_12ms 

Nope, you double configure everything.  So leave Pfsense exactly how it is, and we're going to use the controller to make the rest of the Omada kit dovetail seamless with the existing configuration of the Pfsense, and ideally re-create the switch and AP configs exactly...just via the controller this time.

Your Pfsense will still continue to do all the routing, the DHCP, possibly some ACL stuff, but it's config will plug nicely into the socket that is Omada (so don't expect to do any DHCP reservation, or WAN failover stuff via the controller...that would only work with an Omada gateway)