For Shapespark support for Mac see: Apple Macbook Version? - #8 by wojtek
If upgrading your Windows PC, I’d recommend at least 16GB RAM, a CPU with 4 physical cores and a mid-range NVIDIA GTX/RTX GPU. If your budget is higher, I’d invest in a high-end NVIDIA RTX GPU (RTX 3070 or 3070 Ti or higher), and a CPU with 8 physical cores.
If you would like to work in 3D tools while baking, it’s good to have two GPUs, as baking on a GPU may make the whole system laggy. They don’t have to be of the some power. A stronger GPU would do the baking job in Shapespark, while the weaker GPU would be connected to the display.