First box is your Mac's host name or IP address, like MyMacName or 192.168.X.X. Second is username. Third is password. On the second line, the first box is the share folder name, like VRMovies. The share folder name is needed on Mac, because HereSphere currently can't list SMB shares for Mac. It can only list the contents of the share itself. I'll be adding support for SMB1 in the future, which should provide better SMB share listing capabilities. If it's still not connecting, try restarting your Mac.
I'd recommend looking into setting up XBVR to stream your videos with HereSphere, though. It provides tags, thumbnails, and other useful features.