You Can run your model without GPU. If your computer does not have any it will run on CPU.
You only cannot use learn.fp16() which requires GPU. The network will return results 5-50 times slower.
Fastai2 does not support windows yet (checkout https://forums.fast.ai/t/fastai2-on-windows/)
but if you have windows 10 you can use WSL2 (which is Linux-on-Windows), or Virtualbox or Docker
It will work there, but if you want to use GPU latter its not trivial to configure Nvidia on any of these. (I’m not sure if it is possible, I couldnt make it work)