You don't need special software, the things I have found that I did need was a external hard drive to keep all my designs on. As far as downloading designs, you need to have unzip on your computer, I have a couple on small programs to be able to see what the design looks like, and there are a couple others out there that can resize or do others things to help you. One is called Embird, you can review that on line and also download a trail version before buying it. I have thousands of design on my external hard drive, there are a lot of free ones out there, also embroidery library is a great place to check out, they often have sales where you can get them for around a dollar or so.
If you have I any questions you can PM me.