In your online library at zotero.org you should be able to see the collections and references from your local Zotero library. You can share sources from your online Zotero library with other Zotero users. Group libraries use the cloud storage space of the group creator, which starts at 300 MB for free.
To create a group, click on the Groups tab in your online Zotero library. Click Create a New Group, give it a name, and choose a group type.
Decide what type of access to give group members. This is an important consideration; full privileges allow group members to add and delete citations in the shared library.
Once you have entered membership settings, invite users to join your group: Member Settings > Send More Invitations > e-mail addresses
As members add references to the group’s online library, you can view them by clicking on the Groups tab and then clicking the Group Library link. After syncing your Zotero account, you will see your shared group libraries in a section below your personal collections in your local standalone library.