Adding your Zotero account information to your App is vital because it ensures that your Zotero Library is automatically sycned and backed up.
This is important if you want to use Zotero across multiple devices AND to ensure that if something happens to your core device that your Library is backed up to the Zotero cloud.
This is also key if you want to use Group Libraries - syncing makes sure you can see the Group Libraries and all the content that you and your collaborators have added.