I have office 2011 for mac on my mac book pro.
I opened an excel spreadsheet on my partners iMac using Office 365. which opened fine, when it came to saving it wouldn’t let me save it, and said that i didn’t have permission and made it a read only file.
Now i cannot access any of my documents. Word, Excel and al on my mac book pro. but i can on the iMac in office 365?
Not sure what your question is as it pertains to a WD My Cloud. From what you asked it appears your trying to save a document to your partner’s iMac. Is this not the case?
If you really are trying to save a document to the My Cloud then check the status of the Share in the Dashboard. If set to Private, ensure the User account one has used to access the Share has the User permission on that Share set to Full Access.