Document type & does not exist

What causes this issue?

You have entered a document type which is not maintained in SAP
ArchiveLink Customizing.

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

Please enter a known document type or, as system administrator,
maintain the new document type.
<DS:TRAN.OAC2>maintain document</>

Error message extract from SAP system. Copyright SAP SE.