Hey,
that is a nice setup and will allow you to run a lot of stuff on your server 🙂
Some things to consider:
You can only us the boot drive for the OS, 32GB are more then enough, 500GB are overkill, but you can still use it
with 2 drives, Hexos will create a mirrored pool, which means you will have the capacity of 1 drive (4TBs in your case) and you can lose 1 drive. Additionally a mirrored Pool cannot be extended. If you want to have the possibility to extend the pool in the future, you need to have at least 3 drives now to create a RaidZ1. A RaidZ1 can be extended with additional drives in the future and you will have the capacity of your smallest drive * (the number of drives - 1)
Your Motherboard has a Realtek NIC, which have a tendency to not work well or at all with Hexos. It's a new 5Gbps NIC which might work better, but keep this in mind if you face network issues.
Hexos is an awesome, easy to use OS and offers exactly what you need to get started. It offers both Plex and Jellyfin as 1 click install apps, so that you have the choice what you want to use. It also offers other popular apps as 1 click installs and more apps will be supported in the future.