As in the picture, there are three 'Login Type' for 'Store Manager for BigCommerce' app
A set up video is included on respective login screens to understand and facilitate the exact set up steps.
In terms of functionality, each login provides the same functionality inside the app currently.
For the technically involved, 'My Store Oauth' and 'BG Single Click' both support v2 & v3 APIs. 'My Store Private Key' only supports v2 API (BigCommerce limitation). As we add more functionality to the app, it is possible (at some point) that some advanced features may only be available with 'My Store Oauth' and 'BG Single Click'. Hence, if you are a new user for this app, we recommend using 'My Store Oauth' or 'BG Single Click'.
In terms of billing and available subscriptions, 'My Store Private Key' and 'My Store Oauth' subscriptions (and billing) are done by iOS/Android app stores. Each of menu items are individually priced (between USD 0.99/month - USD 4.99/month) and users can choose the items they want to subscribe to. Many of our users starting a new store sign-up for 'Orders, Shipment & Tracking' and 'Dashboard' product to begin with and then add more features later. Each of the subscription are portable between 'My Store Private Key' and 'My Store Oauth'.
'BG Single Click' provides a product bundle available through BigCommerce marketplace at discounted price with multiple features bundled together. The base product combines order management, product management, customer management & sales dashboard. Additionally, you can add marketing management tools featuring coupon, website banners & gift cards.
You can choose to subscribe either through iOS/Android billing by choosing 'My Store Private Key' or 'My Store Oauth' to login. If you are interested a bundled discounted product, 'BG Single Click' will provide better economics.