The Windows 10 Timeline provides a way for you to review files and Web pages that were edited, sorted by the day the files or pages were opened. Pressing on an icon should open the Web page or Office document file again.
When Google Chrome is set to be the default browser, the file will not open for editing. Instead, the file is downloaded to the device and the local copy is open for editing, and auto save is turned off. This is the way that Chrome handles file downloads. Microsoft Edge and Firefox users to not have this problem.
Workaround
Use Microsoft Edge or Firefox as the default browser if you plan to make use of Windows 10 Timeline.
Additional Information
excel - Files downloading instead of opening in Chrome - SharePoint Stack Exchange