As the Instagram Graph API is an integrated part of the Facebook Graph API, you can use the Skybrud.Social.Facebook package for authenticating with the Facebook Graph API, and then use the obtained access token to make calls to the Instagram Graph API:

@using Skybrud.Social.Instagram.Graph

    // Initialize a new service instance from your access token
    InstagramGraphService service = InstagramGraphService.CreateFromAccessToken("Your Facebook access token here.");

    // do your thing here