Error occurred in deployment step ‘Install App for SharePoint’: Sideloading of apps is not enabled on this site.
Download :http://www.microsoft.com/en-us/download/details.aspx?id=30359
Or
Enable the Developer feature on your Site collection where you want to deploy and test your apps using Visual Studio. Since this feature is hidden you will not see it in the list of the site collection feature, so you will need to enable it using PowerShell:
Enable the Developer feature on your Site collection where you want to deploy and test your apps using Visual Studio. Since this feature is hidden you will not see it in the list of the site collection feature, so you will need to enable it using PowerShell:
Enable-SPFeature e374875e-06b6-11e0-b0fa-57f5dfd72085 -url http://SPO2013.com
Or
The issue for me was I did not create an app catalog for the webapplication I was trying to deploy. Go to central Administration page and create an app catalog for the webapplication and once the app catalog is created, retry the deploy and now this worked as expected.
