Hi Mary, my name is Andrew and I'm an Independent advisor here to help you.
I’d recommend that you refer to the following support articles to get information, which you need.
Windows Defender Application Guard overview https://docs.microsoft.com/en-us/windows/securi...
Introducing Windows Defender Application Guard for Microsoft Edge
https://blogs.windows.com/msedgedev/2016/09/27/...
Thanks,
Andrew N.