Starting from 1 September Google has started running mobile friendly test. This test is for those sites that appear in search result, but when you click, it prompts to install app.
Google mentioned that these kind of sites frustrate users asking them to install app to see the content. When anyone search something, the intention is to see the content. So asking them to install app is annoying.
You can see the test result in your Webmaster Tool –> Search Traffic –> Mobile Usability.
This is a warning from Google to stop doing such act. Starting from 1 November, any site who prompts to install app instead of showing content, will not be considered Mobile Friendly. This would have great impact on site’s SEO, and would end up loosing ranking from Google Search when users browse through mobile.
However, you can implement a banner on your website to let the users know that you also have a mobile app that users can use as alternative. To be honest, this is the right thing that Google has implemented. How do you feel when you look for something and you are asked to install app instead of showing the content? So stop forcing users to install something they don’t want to.