How to download Library files from SharePoint
Do you want to download Library from SharePoint Online or On Premise, Let us check several ways:
1- You can use the Microsoft OneDrive Sync button from top right corner of library
2- You can use Open with explorer and copy all files.
4- If you are on Premise you can use a script like the one mentioned in this link
5- Download documents from SharePoint Online Document Library using PowerShell
6- Use 3rd party tool like Colligo Brief case
Helpful Links:
SharePoint Virtual summit Videos available
SharePoint Online Page Diagnostics Tool
Checklist for migration between SharePoint versions and new farms