Update your post to include full system hardware specs and OS information.
Include Case and PSU information.
The key to resolving the confusion is knowledge.
You must start with the applicable component documentation: motherboard, fans, rgb watercooler, control hub, and case.
Read the User Guides/Manuals to be specific. ( Verify that you have the correct manuals and be aware that there are often different versions.)
For the most part the documentation will show or otherwise provide how the connections must be made and configured. Often the documentation includes warnings, fine print, and referrals to the manufacturer's respective websites for more up-to-date information.
The motherboard is a good starting point. Look at the fan connection options and requirements. The connectors are labeled as are the pins and voltages.
Does the motherboard support RGB?
You will need to sketch out a diagram showing the motherboard connectors, the control hub connectors, the fans, and connecting cables.
Very good chance that you will need an adapter or two for when "won't fit" happens. The problem is that an adapter (and there are many out there) can create a physical fit but if the pins are wrong the results may not end well.
Pay close attention to connector and pin labeling. Generally the connectors and cables are labeled much the same but may vary with some abbreviation.
There are some standards but not every manufacturer follows those standards. Details matter.
Google "how to connect RGB fans diagrams images" to get a general sense of how the connections may be made.
Plan it down pin by pin be it 3 pin, 4 pin, fan, hub etc....
Here is a reference link to illustrate what you must work out with respect to the fan connections:
https://linustechtips.com/topic/927212-ultimate-guide-to-fan-rpm-rgb-ecosystems/
Just an example
not how you should make your connections.
And you can easily find other newer and likely more up to date references.
Take your time, read carefully, and match it all up.