Here are some example promotional materials you can use as a template to design some for your event.
Excitement Promo - Send this out a few weeks early to let attendees know that they will be receiving an email to gain access to the app. Having this ahead of time your attendees will be much more likely to open the invite email:
Onsite Card Front - The onsite card (front/back) can be printed 2sided onto 4x6 cards. These can be handed out as a quick reference so attendees will know where to go do download the app. And what benefits the app provides :
Onsite Card Back:
Onsite Single Page - Similar to the onsite card, but these are all on one page. These can be hung up around the venue. Or placed on tables in the exhibit hall, or meeting tables :
*Original sizes attached as a .zip