There is nothing sketchy about this - it's just a marketing tool we are using to promote our app.
Then if you're just doing a quiz, why on earth people will forced to download it? You can make a quiz via forms with promoting your project too, I've seen some projects did it in the past.
Because the more people that have the app, the more useful/attractive it becomes. The quiz is an incentive to download the app - a promotional/marketing tool.
The app is needed before PASS tokens can be activated and transferred/sold on exchanges anyway, as detailed here:
https://medium.com/@blockpass/user-guide-to-activating-pass-tokens-128b44648bd2