When you type a search in the address bar of Microsoft Edge you get this error:
You’ll need a new app to open this site
Look for an app in the Store
You get this because you’ve tried to use a search query with a colon in it. For example, you may have typed “site:itsupportforum.net chromecast“. While this would be a perfectly valid search in Google and you’ve set your default search engine to Google in Microsoft Edge, Edge thinks that you are trying to use some strange new protocol (site:). Therefore Microsoft Edge asks you to open the site in a new app (one that supports the protocol).
To fix this, go to the website of your search engine and type the query in there instead.
You certainly don’t need a new app to open the search site.