You have two record types: ACME_Student and ACME_Class.

To establish a many-to-many relationship between two record types in Appian, you should create a junction or mapping record type that will handle the many-to-many association. This new record type should have two one-to-many relationships, one to each of the original record types (ACME_Student and ACME_Class). This setup allows each student to be associated with multiple classes and each class to be associated with multiple students.