Can you read the RGB fan model or part number from the rear side of the fan center? Since i have hard time finding out the exact model of those stock RGB fans. So far, they are either MasterFan MF120L RGB or MasterFan MF120R RGB.
Though, this much i can say, fans have 2x connectors, one for RGB and one to power the fan. And to connect the power connector to you MoBo, do line up the fan connector with header as much as you can before pushing the connector into the header.
Also, to which MoBo headers you're trying to connect the fan connectors?