In order to be able to create codes using a specific prefix, you will need to be added to a group that contains the prefix (see Ad-ID Glossary for descriptions). The administrator of the group can add you.
If someone within your company already has access to a group containing the prefix, they may be able to give you access if they are an administrator of the group. Otherwise, you can contact customer service for assistance.
If your company does not yet have access to the prefix, for example, an agency starts working with a new client that has a registered prefix, you will need permission to gain access to the prefix. Please contact customer service to determine if Ad-ID has a contact for the advertiser to which the prefix is registered. If so, we will reach out to our contact on your behalf.
Otherwise, the agency should have their client send an email to customer service with approval to give the agency access to the existing prefix.
If you would like to check if a company has a registered prefix, see How to determine if advertiser/client has a registered prefix.