have read your post and it was slightly confusing.
So your problem is with mapping the My Cloud to you Mac. The following link may help. It appears to possibly be a two step process.
From that link note the following text under mounting the network drive:
… or for a specific user check the box next to “Remember this password in my keychain” – you must select to remember the password otherwise the automatic login event can not happen without logging into the network drive
