Will this DDR4 Ram work for the ASRock AB350M Pro4 Motherboard?

Solution
Your board only supports Dual Channel.

But yes that Memory will work. However for your best performance buy the fastest memory in your budget, 3200 is the sweet spot for Ryzen.
Combining multiple kits have no guarantee to be compatible together. Such combinations are done on a "Do It Yourself" compatibility testing basis.

Such combinations can cause the PC not to boot or the memory to be unable to operate at rated specifications any longer.
 


I plan on getting a 2x4gb like 2666mhz then maybe another set of it later so i would have quad channel 16gb
 


Well i plan on getting the same set later on, a 2x4gb 2666mhz, so i would have 16gb, the board has 4 ram slots