Sharing is the ability for multiple people to have access to the file while Co-Authoring is the ability for you and your colleagues to open and work on the same file at the same time. Co-Authoring has been built into Word and Power Point starting with Office 2016, but unfortunately Co-Authoring is not a feature added to Excel 2016 or Excel 2019. Co-Authoring is a feature added to Excel 365 locally installed or Excel Online Versions.
If you want to “Co-author”, then you and your co-authors will either need to use Excel Online or have Excel 365 installed.
If you want to use Excel 365 locally installed, you can log into office.com and select the Install Office button in the upper right-hand corner to “upgrade” your Office 2016-2019 version to the Office 365 versions. In order to “Co-Author” in Excel 365 locally, you will also need to turn on the “AutoSave” feature in the upper left-hand corner.
For those that don’t want to install Office 365 locally, you can click on the file in Teams to open it, and then select the Edit button to edit. Additionally, there is an Open menu option pictured below. Co-Author is available in either option 1 or option 3 (the default action). While Excel online and Excel in Teams options provides for Co-Authoring, they do not provide all of the other advanced features that Excel running locally provides. Only Office365 includes both the Co-Author and advanced built in features for Excel.
