I need to add in Data Studio metrics my apps in Play Store and AppStore, like 'number of installations'. I searched for free connectors in Data Studio, but didn't find any. Apps metrics should update automatically. Are there any ready-made solutions for this problem?
AFAIK, there is no ready-made solution. However, Play Store supports exporting data to Google Cloud Storage.
You can surely connect to this data using Data Studio (using the standard connector for GCS) or even create a dataset using BigQuery.
For AppStore you'll probably need a hand-made solution.