There are three types of Zotero groups.
Private Groups
Public, Closed
Public, Open
For more information on Group Types, please see the Zotero Groups documentation page.
Groups allow you to share citations and files with other people.
For more information on Zotero Groups, please see the Zotero Groups documentation page.
After you create the group, you can invite members by clicking on 'Members Settings' and then 'Send More Invitations'
Add email addresses of prospective members. Library/Group members will receive an email from do-not-reply@zotero.org
Once members join the group, they will need to sync their Zotero accounts before they see the group in their Zotero library. To sync your Zotero account, click on the green circular arrow in your Zotero account.