For some browsers/operating system configurations there are sometimes issues opening the app because of your cookies settings.
Because our app opens as an iFrame within the shopify domain, this can trigger some browsers security features, usually having to do with cookies.
Try the following:
Open your browser preferences and find the security settings, and make sure you are allowing 'Cross site tracking / 3rd party cookies', then clear your cookies, and quit and re-open the browser. Then try to open the app
Or try a different browser. If you don't have another browser
Then you can try loading the app within the Shopify iOS app
Or, try loading the app from your phone's browser
If none of that works, send an email to email@example.com and send a screenshot of what it looks like when you try to open the app, and please include your browser and version number, and operating system version as well.