Material group & created. Additional material maintenance desirable

System Response

The material group was created successfully. The respective materials
were only created in an outline form and need to be completed.

How to fix this error?

Choose Goto -> Material group material in the menu or press the button
"Material group material maintenance". You access material
maintenance. Maintain the material group reference material there in as
much detail as possible. You can use it not only as a user-friendly
input facility but also as a reference for all material data belonging
to the respective material group.
If you entered new value-only materials, you should also maintain the
respective material group materials and/or hierarchy materials,
particularly the respective (plant-dependent) tax classification.

Error message extract from SAP system. Copyright SAP SE.