I just bought the Keurig Duo-Plus and the universal K-cup was included with my purchase. Step 5 is very important. Like many of you I got very frustrated and thought it didn’t fit.  You have to remove the K-cup pod holder from your machine before inserting the universal k-cup.  Works like a charm! I love my new Duo-plus! Keurig my suggestion is clearer instructions on how to remove the pod holder from the machine prior to placing the universal k-cup.