Why am I presented with a blank screen when I install or open the app?
99% of the time, this happens when you are using the Safari browser and it can be solved simply by using a different browser (such as Google Chrome).
This is because of a known issue with how Shopify authenticates apps and we are currently working on a fix for this.
If you're not using Safari and having problems installing or opening the app then please try clearing your browser cache.
If you're using the Shopify app on your mobile device, there's a bit of information here on the requirements; https://help.shopify.com/en/manual/shopify-admin/shopify-app