I want to use Instagram API
to get the latest images based on a specific tag.
When I use:
https://api.instagram.com/v1/tags/{tag-name}/
You are in Sandbox mode, so it will return only media from your sandbox authorized user, here is information about this:
As another example, let's consider an endpoint that returns a list of media: /tags/{tag-name}/media/recent. The response returned by this endpoint will contain only media with the given tag, as expected. But instead of returning media from any public Instagram user, it will return only media that belongs to your sandbox users, restricted to the last 20 for each user.
Here is the link to more details about Sandbox mode: https://www.instagram.com/developer/sandbox/
Once your app is approved, you will see all media.