You are not authorized to create documents; document &1 not created

What causes this issue?

You want to execute an activity to attach documents to the task.
However, this activity requires authorization to create documents in
the document management system (DMS). You are not authorized to do this.

System Response

The document &V1& was not created in the DMS. The system cannot process
the task.
If the document you wanted to create was previously sent via e-mail, the
e-mail will reach the recipient. However, the task status will not be
changed.

How to fix this error?

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

INCLUDE NA_SYSADMIN1 OBJECT DOKU ID TX

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.