You need the standard developer authorization profile to create ABAP development objects.
A DDL source allows you to define an entity that represent as a projection onto one or multiple database tables. With the DDL source you have the appropriate ABAP development object, which you can use directly to access the standard ABAP Workbench functionality (transport, syntax check, activation).
The maximum length for names of DDL sources is 30 characters.
In the selected package, the ABAP back-end system creates an inactive version of a DDL source and stores it in the ABAP Repository. In the Project Explorer, the new DDL source is added to the Core Data Services folder of the corresponding package node. As a result of this creation procedure, the source editor will be opened. Here, you can start defining a CDS entity.