You don't need to worry about port forwarding to connect the Apex to the internet let alone Fusion. The only purpose port forwarding would serve is to allow you to connect to the defaults web interface that you would normally access via the IP address.
Is this the classic Apex or the Apex 2016? If classic, use the display to go to system/network and make sure DHCP in enabled. if it's enabled, that will get you connected to your network assuming you are hard wired to your router and not using a wireless bridge. If you are using a wireless bridge, then you first need to get that connected to your network.
This is the Get Started instructions for a new Classic Apex.
https://www.neptunesystems.com/getstarted/apexgold/
Get Started for Apex 2016.
https://www.neptunesystems.com/getstarted/apexng/