After upgrading from a Nexus 5X, I found a bizarre issue with my new Samsung Galaxy S9. Fresh out the box, I couldn't install Instagram (currently the 10th most popular free app on the Google Play store).
A quick google search shows that others had the same issue.
Here's how I fixed it:
1. Open Settings > Apps and find the Google Play store app.
2. Uninstall updates by tapping the ellipsis, it should be the only option.
This alone worked for me. After installing Instagram I was able to update the Google Play store app and not have this issue again. Happy hunting.