Recently when I was trying to add Napa Office 365 Development tools to my Office 365 SharePoint online site, I got an error which says:
We need your help to make this app work:
Turn on Developer Feature
And also the ADD IT button was disabled.
The error looks like below:
The solution is to create a developer site. You can check out this article to know how to create a developer site.
SharePoint 2013 online provides a developer site template which we can use to create a developer site.
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