Summary of the steps:
This video describes why and how to transfer the Zotero database and Pdf articles from the Zotero folder inside your favorite Cloud folder (here, Google Drive, for the example).
This tutorial describes how to set up manually the library you want to connect to ZotEZ². With
ZotEZ², you have the possibility to force the app to go to one specific folder on your Cloud.
This means that you can have multiple library on one cloud (let's say Dropbox), and still be able to choose which one will be synchronized with ZotEZ²!
It also means that you can have your database file (.sqlite) in one place, and your library folder in another place!
Finally, it implies that you can use attachments rather than direct storage folder linking of the PDFs.