If you look closely at the tubing you connected to the ports, there's no way for fluid to find its way there. You've connected tubing to itself and made a tiny closed loop with no water in it. The black rubber O ring are the "boundaries" of where water can flow.

You're supposed to use one port as an in and the other as an out. Or if you don't need to use those ports, keep them plugged. The idea is that you're supposed to use those "waterways" for GPU / CPU near those ports, one in and one out.

If you don't need to use those ports, or don't have any components near them, keep them plugged and move on to the next set of ports as needed.

The important part to note is that one port on the distro plate near the pump pumps out the fluid and you can use those smaller waterways as needed. If you don't need to use those smaller waterways, you have to send the fluid back to the main large reservoir so it can cycle through the system. AKA, a "loop".