Hey you!
It's a lil different on Win8, try removing the prompth for a password by doing as following (also add your homegroup to the share permission):
Open Advanced sharing settings by swiping in from the right edge of the screen, tapping Search (or if you're using a mouse, pointing to the upper-right corner of the screen, moving the mouse pointer down, and then clicking Search), entering advanced sharing in the search box, and then tapping or clicking Manage advanced sharing settings.
Expand All Networks, tap or click Turn off password protected sharing, and then tap or click Save changes.
Best Regards
Kimzi
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