OK, you have what you require, just need some detailed info.
First, the Rosewill fans include a particular type of lighting device (there are two incompatible system in use) called Addressable RGB or ADDR RGB or ARGB lighting. These require connection via a THREE-pin mobo header, and you have one! See your mobo manual on p. 7-8 (in Adobe reader, it's p. 13-14), and items 23 and 24 in the bottom left (rear) of the mobo. Item 23 is the 4-pin plain RGB header you speak of. Beside it is item 24, a 3-pin ADDR RGB header (looks like the 4-pin one, but with one pin missing) and that's what you need. You also will need to install ASRocks' software utility called ASRock Polychrome RGB which can control ADDR RGB items attached to that header.
Now, also look up the manual for the Rosewill fans available for download here if you do not have it already
https://www.rosewill.com/download/rgbf-s12001_usermanual_a-pdf/
The RGB Fab Hub connection diagram shows two cables to attach first. One goes to a SATA power output from the PSU for power. The other has two connectors on one end, one each for different mobo 3-pin ADDR RGB headers. I expect you'll need the one labelled for ASUS and MSI mobos. Then each of your fans plugs into a FAN port on the Hub.
Regarding fan speeds, it appears there is no way to have the mobo control them from its fan headers. The Rosewill Hub allows you to set their speeds manually with buttons on the remote control box.
Regarding RGB lighting effects, the remote control box offers you two options. It has on / off buttons at top left, and the Off button shuts things down. But the On button does two functions. Press it once and the system starts up. When running, pushing this button switches from control of the RGB lighting effects by the Rosewill system (use buttons on the remote to do this), or to giving control to the mobo's ASRock Polychrome RGB utility to control them via the mobo header and the cable from it to the Hub. Another push of the On button switches back.
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