If you cannot download/use the app, you can still use your reservation.
Here is how you do it:
If you are using the link in the confirmation email to open the entrance/exit, please delete the app and follow these steps:
At the bottom of the email, it says: "Have questions or need help?". Below this, it says: "Open your booking here online." If you click on "here online", you will be redirected to the access page. You can then use this access page to open the entrance/exit.