Yeah, it's not a Ryzen issue though, it's just that the board manufacturers and Intel/AMD want everybody on Windows 10 so they don't have to support multiple versions of totally incompatible driver frameworks, and Microshaft wants everybody on it so they don't have to continue to expend resources on having to support three or four different operating systems and all the drivers for all the possible hardware configurations. Hard enough to do for just one operating system, much less a bunch of outdated ones.
Now that you have windows working, you need to go here:
www.asus.com
Then select Windows 7 as the OS type, and then download the applicable drivers for chipset, audio controller, storage controllers and network adapters, as well as the USB drivers, and install them. As I mentioned before, updating the BIOS is pretty much mandatory on Ryzen boards if you want everything to work, so make sure you have the most recent version of the BIOS firmware installed. It's particularly important for memory support, but it affects other areas as well.