Enable "Share Workbook" Button
Newer versions of Excel 365 now hide the Share Workbook Button by default. To restore the button to your Tool Ribbon in Excel, follow the steps on this page. The Share button now connects to OneDrive or Sharepoint instead of the previous sharing method. It is recommended that high-collaboration files are moved to SharePoint, MS Teams, or OneDrive as these platforms offer more features for collaboratively working with files.
More information from Microsoft about Sharing Workbooks and Collaborative Working Platforms are available at the following links: