Users are able to tag their send outs to organize documents and make them easier to find. To ensure your tagging system does not get out of control, we limit users to the tags their admin creates in the Tag section under the Settings.
The admin of the account can go to Settings > Tags and click Add Tag to begin creating the tag library. Name the tag and be sure to set it to Active. Do this for all the tags you want to be available to the users of the account.