You need to download the manuals from deepcool and gigabyte.
Deepcool fans:
http://deepcool.com/product/dcoolingaccessory/2017-07/12_6835.shtml
MB gigabyte (page 14)
https://www.gigabyte.com/us/Motherboard/B450M-DS3H-rev-10/support#support-manual
Read the manuals you should be able to connect them, also keep in mind the MB RGB header can only support up to 2Amp, three fans should be fine, for the 4th fan, you have to check all the fans to see what total Amp they will draw, if they draw less than 2Amp, you are fine to use 4 fans, otherwise you can't use 4, because if the fans draw more than 2Amp, they will kill the RGB header and the MB. One more the deepcool fans are the RGB (12V/G/R/B) type, and your MB has the RGB (12V/G/R/B) header only, so you have to buy other RGB (12V/G/R/B) fan, and not the aRGB (5V/D/G).