Appaloosa can only register users using Safari Mobile on iPhone, iPad and iPod Touch.
Other browsers, such as Chrome or embedded browsers or Gmail won't allow access to store or apps.
Make sure your users are always using Safari to install the store or apps.
If one of your users is still facing issues, please have a look at our troubleshooting articles and contact us via the live chat if you need additional help.
The following information will help us investigate :
the email of the user
the device they're using (iPhone model, iPad, OS version)
try to know where exactly the user is stuck and what kind of message they're seing on the screen. Here's what the normal store installation process on iOS looks like.
if possible a video ; here's a tutorial to record an iPhone screen