Important Microsoft no longer recommends creating and using Access web apps in SharePoint. As an alternative, consider using Microsoft PowerApps to build no-code business solutions for the web and mobile devices.
You don’t set permissions on an Access app directly. Instead, you set permissions on the SharePoint site where you create the Access app. This video shows you how to set permissions on the site where your app was created, assuming you don’t need to create another site first.
If you already created an app and now you want to set different permissions for the app than for the site where you created it, follow these steps: