You were not supposed to substitute your line with what I posted. It was so that you could review, compare and make changes to effect the permissions needed (add/replace). Many people are using CIFS/SMB/NTFS with Emby on Linux. It can work just need to sort it out. Removing the credentials is likely what caused it to fail. For the uid/gid you can use either the names or numeric values.  Try this: <host/share> <local path> cifs credentials=/etc/cifs-credentials,rw,