1. At https://www.zotero.org, login to your account.
2. Go to https://www.zotero.org/groups/new.
3. Choose a name for your group, and choose the type of group .
4. Set and save your Group Settings and Library Settings.
5. Under Members Settings you can designate roles for members and invite new members. You can send the invitations using email addresses or Zotero usernames.
Member roles are:
To create a new group, click on the "New Library..." icon located next to the New Collection icon in the top left corner of Zotero. When you click on the New Library icon, select "New Group" from the drop-down menu (demonstrated below).

When you select "New Group," you will be brought to this page on Zotero's website where you can create a new group.

Group Types
There are three different types of groups for Zotero users: Public, Open Membership; Public, Closed Membership; and Private.
Public, Open Membership
Public, Closed Membership
Private Membership
Once you have created a group for your project, you need to invite members. To do so, go to the Zotero website, click on the Groups tab, and then on the "Manage Members" link. On this page, there is a link that will allow you to invite users, so be sure to have the emails they used to create their Zotero accounts handy!

To add items to your Zotero Groups, simply drag and drop the items from your Zotero Library into the desired Group Library folder. If you would like for group members to see changes to the Group Library, make sure that they have enabled data syncing.

Enable Data Syncing and your group library will appear in the Zotero client in the left column. Personal and group libraries are completely separate, although items can be copied between libraries by dragging them back and forth. Any items dragged into groups are separate copies, so if you make changes to an item in a group library, those changes will not be reflected in the copy of the item in My Library (unless you drag the item back into My Library.)
If you create a group and enable file syncing to Zotero, any files synced will count against your personal storage allowance of 300 MB. If you want to purchase additional storage for a group, you may want to create a new Zotero account with an email address not associated with a person, but rather an organization.
Group Members Can Not Add or Edit Documents
The settings to manage who can edit the group's library and edit file attachments are located on Zotero's website under Groups, then the group you're using, then Library Settings, then Library Editing and File Editing.

There are two main options available here:
Items Are Not Showing Up for All Group Members
The most likely reason for this is that the owner of the group has filled up their quota of free space. The owner of the group can check on this by going to Zotero's website, logging in, clicking Settings, then selecting Storage.

If the owner has used up all of their storage, then they have two options:

