Hi John,
The file explorer is available in the Trimble Connect for Browser as before (as per the documentation link you shared) . We haven't made any changes to that. It should work . If you are facing issues accessing it, please share the project details with our Support team (connect-support@trimble.com) . We will investigate.
In the Web 3D Viewer, there is a back button available which allows you to navigate to the file explorer as well (if the 3D viewer was launched from Folder hierarchy) . Please let us know if you need any further help.
Regards
Darshan Kamat