The Content Chooser supports five types of Libraries, «SharePoint Online» libraries, «Teams» libraries, «OneDrive / OneDrive for Business» Libraries, «Unsplash» libraries, and «Samples» libraries.

Switching between libraries

Template Chooser Setup SharePoint Online

To switch a library just click on the name of the existing library (1) at the top of the Add-In. That will bring up a list of all available libraries for you to choose from. You can then just click on one of the libraries to switch.