When you order Memory maker, you should get a confirmation number. Mine was 4 letters followed by numbers. I went my
MDE account and added it. You can find the place to add it by going to My Reservations and Tickets in MDE, and then clicking on the Link Memory Maker button.
If you purchased Memory Maker on the Photopass website or through ticketing, you should get a Memory Maker card in the mail. There is a code on the back of the card that can be added the same place in MDE.
Per another thread, if you have added it to your reservation or some purchases online, there is a bug in their system where you will not get an email confirmation. You will need to call TICKETING to get your Memory Maker number (NOT reservations), or print a copy of the confirmation screen of your purchase on the computer.
I really hope that everyone on my account can use the Memory Maker. We do not have separate accounts - I manage everyone. I made DH my manager of the Memory Maker thinking that he would be the one to get the ride photos and that it still needed to be the primary person. Hopefully that is not true. Hopefully, I will have access to the pictures as well, seeing as Disney does not have a separate email for DH. We shall see.
I have heard of people missing pictures. I hope that bug has been worked out.