@johnludena - Actually, I did! If you read the directions, it talks about a "Mijireh Private Checkout" page being created. Its not your checkout page that is normal - its looking for another one! So, make a page, and add the {{mj-checkout-form}}, Slurp that NEW page, and voila.. It will work.
The whole problem was that the page that was supposed to be created, wasn't being created.