Welcome to BBR,
I'm not familiar with that particular router but in general all you need to do is set up port forwarding so connection attempt from the Internet is routed to the camera. You already know the camera is working fine locally.
I could not find a detailed user manual just this:
If you need looks like they have a help desk:
By default NAT drops all remote connection attempts because unless explicitly configured it does not know which device on your LAN the request is intended.
For port forwarding to work you want the camera's IP address to remain the same. In general DHCP will keep assigning the same IP to the device when it asks to renew the lease but the address might change if camera is turned off for a long time. Most routers have a way to bind IP address for MAC address. That gives you the advantage of a static IP address without the hassle of manually configuring the camera. Or you could configure the camera with a static IP address. If this last paragraph confused you ignore it and see what happens.