You have to choose between the sense of automatic and manual fan speed control first. Automated control doesn’t make any sense since RPM ranges are fixed and no one has any idea what optimum RPMs between low noise and safe cooling his/her self-built PC needs at certain room temps. Even if known, the range can only match an RPM curve that makes sense by accident anyway.
Automatic control can only be done by mobos, manual control with potentiometers works with power from mobo as well as PSU. Since it’s better to connect fans to the PSU to not have such unnececessary current on the mobo PCB, buying a fan controller like you did is the best solution.
However it should be an electronic one with programmable temp alerts and you should program low temps into it and find a good balance that in case of any doubts tends more to cool CPU/system than to a silent PC.
Unfortunately there’s no air cooled PC with everything around 20Â°C and absolute silent operation…