Hi, I was having this same problem. This is what worked for me: Went to settings on my mac, then file sharing, options. Then I checked the box under "on" next to account name. It worked right away. I clicked on my macbook in windows 10 and entered the same username and password I use to login to my mac it worked. Before changing this setting, I would get a message that the username or password was incorrect. Hope this helps (and makes sense because I don't really know a lot about computers). I know this post is old, but maybe someone will get some use out of it.