Can we install Microsoft Office on a Windows server for simultaneous multi-user access?

No, Office licenses cover desktops using office. If you remotely access Office you must have a license for each desktop doing so.

"Every device that uses Windows Server Remote Desktop Services to remotely access Microsoft Office requires a Remote Desktop Services CAL, in addition to Windows Server CAL and a Microsoft Office license. Dedicate a Microsoft Office license for every desktop on or from which you plan to use or access Microsoft Office, even if that use is only occasional.

See: Microsoft Volume Licensing Brief - Licensing of Microsoft Desktop Application Software for Use with Windows Server Remote Desktop Services (from the Internet Archive)