When importing into Wordpress, the importer needs to check to see if it has to either insert a new record, update an existing one or delete it. To do this it uses a set of unique identifiers which are used as a reference.
The No unique fields present error suggests that you have not entered a unique idenfifier field such as , taxonomy term importer requires either: name, slug, or term_id. User importer requires either: email or login/username, and post type importer require either: ID, slug, or name , these can be modified via functions.
The Record is not unique messages suggests that the importer has found multiple records matching one of the unique identifier fields for your import type and it does not know how to proceed.