I don't know what "Edirol" (generic) means. That's why I ask for the model number. What I'm suggesting is that your current keyboard controller does not work with Windows 10 using the USB connection because there is no driver that makes it compatible with Windows 10. However, your current keyboard controller will work fine with windows 10 as long as you connect the MIDI out and MIDI in to an Audio/MIDI interface.
Example; Behringer UMC204HD interface works with Windows 10 via a single USB connection since Behringer makes a driver that works with windows 10. The UMC204HD has standard MIDI in and out jacks. This means your computer will be reading what is happening at the UMC204HD and doesn't care what midi device you have connected to it. And "voila'" midi in and out to Band In A Box. Well, Midi in is all you really need.
UMC204HD is $80 US at amazon.com.
There are many other audio/midi interfaces that do this.
Since you are headed toward Coyote, a software synth, for your sounds maybe you don't need an external hardware synth at this time. Maybe getting your current midi controller working via midi cables might be the way to go.
For me, I rarely use external hardware synths anymore.
BTW, I think you can get the Cakewalk TTS-1 General Midi software synth for free if you install the free Cakewalk By Bandlab. It is similar to Coyote softsynth and very simple to use.

Does the noise in your head bother me ?