One of the big reasons Microsoft has touted keeping up to date on its Office suite and moving to Office 365 is the ability to work with others simultaneously on the same documents. When working with a team on documents it can be a hassle to wait for each other to save changes and exit files. This can be made simpler with a Document Management System, like SharePoint Online, but that doesn't necessarily allow you to WORK on the same file at the same time. Two pairs of hands in an Excel workbook at the same time can be twice as powerful as one.
To use the real-time collaboration capabilities of Office, you should consider getting Office 365. Not only can you license web-based versions of Word, Excel, and PowerPoint -- but you can also get Microsoft OneDrive which is a simple way to store, save, and share files online with others. Think. . . Dropbox or Citrix ShareFile. Depending upon the version of Office 365 you purchase you may also get Exchange Online, SharePoint Online, and Skype for Business. While that may sound like overkill -- a monthly user license can start for as little as $12 a month depending upon the size of your team. If you are a small or medium business -- this move can not only standardize your versions of Office across your company but also unify and replace older Exchange or non-company branded mail services like Google or Yahoo or. . . dare I say AOL accounts?
Once you and your team are outfitted with your Office 365 licenses you can start sharing and working together. The quickest way to get started is to save the files you need to share in your OneDrive then invite your other licensed team members to work with you. Remember -- working by yourself is boring -- working with others is fun. . . think like Tom Sawyer painting a fence!
For more details check out Microsoft's Support on Office Online Collaboration.