Why is out of office grayed out on office 365 for mac

I have to save and backup Word and Excel document files in a manual way. However, I tried on both Word and Excel applications, the AutoSave was not available to work.

I tried to turn on the AutoSave feature in the Excel and the Word so that I can automatically save important files while editing them. ' The Office AutoSave feature seems greyed out and is not available to work in my Office 2016 applications.