Office 2016 is web based. It is possible to sync a local folder with SharePoint, however, often time syncing fails or is so slow that opening a file using a browser actually opens a file that has not been updated. This is annoying, but using some conventions it's not too bad.
Get a Human Readable URL
Each app, say Microsoft Word, has a File screen. The file name is shown upper left. Right click, you'll see a list of options. Select Copy Path.
Which Do I Use Web or App?
In general, the rule of thumb is, if you are writing or editing a document, use the associated app. Always edit using the "http://" path to the document, not a local synced version. Honestly, the synced folder is more of a liability than having any real use.
How Do I Open A File Using http: URL Efficiently?
Using SharePoint 2016 on the web, Select Versions, then right click on the latest version.
Links in Firefox Download the File then Edit in the App, How do I fix this?
If you are not using IE, when you click on a URL which is in SharePoint the file is downloaded to Downloads (save) or %TEMP% when "Opened" from the Browser. Instead, right click on the URL on the page, copy it and paste it into the browser OR open the application and "Open Other Location", then "Browse", then paste into the filename field. This will force the application to use the http: file path, preserving updates properly.
How Do I Get a URL of a Folder To Send to Someone?
Getting the URL of a file or folder is easy, getting one that doesn't look like gibberish isn't.
Getting the URL of a folder doesn't seem possible in 2016 web interface, but can be done my simply clicking on the "..." in the classic interface. In the 2016 interface, you can use the Firefox method to copy the URL of a file in the folder, then just delete the filename.
Using the App... open a file, the go to File/Open File Location. Right click, copy, paste.