Mayflash is indeed as chinese knockoff looking manufacturer as manufacturer can get, but they actually do hardware which nobody else does and they actually work. I have gamecube to WiiU/PC and Pro Controller to USB adapters from them.
That Mayflash adapter isn't native bluetooth dongle. It's its own hardware, which takes DS3 inputs and wraps them up into standard XInput and DirectInput USB controller, making it show up as working controller in the OS. I own the Wii U Pro Controller variant of that and it simply works, which is better with Pro Controller as there isn't simple way to make it work via regular bluetooth adapter. Also because of DirectInput option, it works with PS3 as well.
I'm putting that in the page because it's the easiest way to make it work with PC without using any additional software. Of course for many, software solution is still superior because it doesn't cost anything extra.