I have created a new web application inside my SharePoint 2013 on-premises. Then I created a new app catalog for my new web application. now I went to the app catalog and I add a new .app file as following:
Then I went to a site collection inside my new web application >> Add App >> from your organization >> I select the new app. But I got this error:
Sorry, apps are turned off. If you know who runs the server, tell them to enable apps.
So can anyone advice on this please? Thanks.