RGB pins 4 is nice, but some have different types of it (size/shape) not sure about what those are.
you said it was connected the RGB cables? as you can do either through motherboard pins if the exist or hub, for a hub you would need to know if they will fit eachother and it works by using SATA power and USB port on the motherboard for the HUB. USB for control, SATA is the power.
both is done if you just connect it straight for the motherboard but supports less fans this way.
the pins on the motherboard would be the amount of pins you need, and say something like rainbow *something something* 1 - 4 etc.
then connect just like you did with the power for the fans, just for RGB. (see manual if unsure were, or if they dont exist).
Else you would need some software too, like corsairs ICUE or one that might be from the brand you got the fans.
i honestly, don't know, what you tried... To say.
1 hour ago, diphendum said:
fans are 2 of Scythe's Kaze Flex 140 MM and one 120 MM versions and all have a 4 pin connector.
4 pin = dumb / cheap LED color control. All the LEDs on the fan will produce the same color
3 pin = addressable LED (D_LED), more expensive but allows for different color LEDs on the same fan.