What happens during install, which permissions are requested and why, and what to do if the install screen does not appear.
Every app is installed the same way: from the Shopify App Store, or by entering your store domain on the app's own website. Shopify then shows you a permission screen listing exactly what the app can read and change. Nothing is installed until you approve that screen.
This usually means the app is already installed on that store, or you are logged into a different Shopify account than the one that owns the store. Open your Shopify admin, go to Settings → Apps and sales channels, and check the list. If the app is there, open it directly.
Each app opens a short setup that walks you through the first result: a deliverability scan, an order import, or a theme scan. None of them send anything to your customers until you explicitly turn that on.
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