Processor: CP4
Network: Ubnt Dream Machine Pro with Ubnt L2 switches.

DDNS domain is registered on both MyCrestron.com and on the CP4 itself.

AUTH/SSL is enabled on both the CP4 and the CrestronGo app.

I still do not understand how I'm not able to connect using Crestron Go. Here's how I have everything setup:

UDM Port Forwarding Rules: https://ibb.co/ZXvBkh8
MyCrestron Domain Test Connection: https://ibb.co/MP7dY60

This is my first time working with a Ubnt Dream Machine, although it shouldn't be any different from their other routers/controllers.

Is there anything I'm missing?

First off, I would recommend using a VPN instead of port forwarding to access your Crestron system remotely.  Unfortunately the UDM Pro won't do OpenVPN.  But if you do  want to do port forward anyway, at a minimum, I would recommend changing the port numbers.  In particular, the https and ssh ports.  Some ISP will block common ports like these.  The other thing I would do is limit the range of IP addresses that can connect to the UDM -- otherwise your CP4 would likely be prone to relentless attacks from every Tom, Dick, and Harry.