Check out this link: https://developer.apple.com/help/app-store-connect/view-app-analytics/view-app-metrics

Installations metrics depend on the number of users who agreed to share data with you, whereas the first time downloads has no such constraints so you should refer to the first time downloads in my opinion (source: https://developer.apple.com/help/app-store-connect/view-app-analytics/view-app-metrics)

You can use the internal API "https://appstoreconnect.apple.com/analytics/api/v1/data/time-series" but it's not well documented (https://developer.apple.com/forums/thread/29421) Another option is to use an ELT (extract/load/transform) tool that provides and maintains the connector to App Store Analytics such as Rivery (https://docs.rivery.io/docs/walkthrough-appstore-connect-apps-analytics) In your situation you'd want to use the "Source" as a dimension and retrieve the "total downloads" metrics to get this breakdown. However an ELT tool would work only if you plan on landing the data into a supported target (cloud data warehouse, bucket, email, data lake, etc)

Rivery is a company that can do it in a few clicks: https://docs.rivery.io/docs/connection-appstore-connect-apps-analytics

Hi, You can use Rivery to get data from AppStore and Play Store to get it into a csv or even BigQuery. It's a low-code tool that allows you to integrate and centralize your data, and it has a native integration with App Store Connect: https://docs.rivery.io/docs/walkthrough-appstore-connect-apps-analytics Other ETL tools may also have native integrations with the App Store. Best