You are not authorized to use class & for classification

What causes this issue?

You want to allocate an object to a class. However, you do not have the
authorization to allocate objects to this class.

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?

Choose another function or another object
or
Contact your system administrator to get authorization to classify
using this class.

Error message extract from SAP system. Copyright SAP SE.