An auristatin compound conjugate is provided herein. The conjugate comprises a protein based recognition-molecule (PBRM) and a polymeric carrier substituted with one or more -LD-D, the protein based recognition-molecule being connected to the polymeric carrier by LP. Each occurrence of D is independently an auristatin compound having a molecular weight ≤5 kDa. LD and LP are distinct linkers connecting the auristatin compound and PBRM to the polymeric carrier respectively. Also disclosed are polymeric scaffolds useful for conjugating with a PBRM to form a polymer-auristatin compound-PBRM conjugate described herein, compositions comprising the conjugates, methods of their preparation, and methods of treating various disorders with the conjugates or their compositions.