Hey Mati!
This depends on the VM's networking configuration. If your Meshnet VM is behind a separate NAT, you won't be able to easily access things outside of your VM with it.
Here's a brief documentation article I found: https://docs.unraid.net/unraid-os/manual/vm/vm-management/#configure-a-network-bridge
There is a couple of options you can go with here:
The simplest solution would probably be installing Meshnet on bare metal and forwarding needed ports from the host machine to the VM. This way you can access your Jellyfin container through Meshnet with just the Meshnet IP/Nord name and the :8096 port.
Another way, which I don't recommend (due to the reduction of connection speed), is to set up your VM's network configuration to a public bridge. Then, you can route your traffic through the VM and access the Jellyfin container through its local IP address. Keep in mind you will have to enable local network access and traffic routing permissions for your clients (from the VM) within Meshnet for this to work.