Hello Nweinfeld, and welcome to Seven Forums.
You would only want to select the account that you want to have Windows automatically log on to instead. Since you did this with the other account, that it the one that Windows is trying to log on to automatically. Since it sounds like you did this with the
HomeGroupUser$ account, Windows is not going to be able to log on to it at startup since it's not a real user account.
Try doing a
system restore at boot using a restore point dated before you made these changes to undo them. Afterwards, you should be able to boot up like you did before and try the tutorial again with only your user account instead.
Hope this helps,
Shawn