We're glad you got moving on something that worked for you. For other new users, we can explain why we've built a plugin that requires registering an API client.
In order to display and feed Instagram photos through a website, someone must have registered an API client with Instagram.
There are many other Instagram plugins that use the same API key for thousands of installations.
Using that kind of plugin, you share the risk with all of the thousands of other plugin users that the plugin developer may disappear, may not keep the API client active, and effectively break your site feature without notice.
You also risk the plugin developer eventually charging for their plugin, especially because they're providing an API registration service on which you've become dependent.
The 'Easy Instagram' advantage is that only you (your website) and Instagram are involved, and that still -- you don't need to know any code whatsoever to complete the installation process.
Basically involving a series of cuts-and-pastes, most people report having registered their API client in just a few minutes.
But sometimes there is a snag, which I'll reply about in a new response here.