This is actually Tumblr to Twitter, all you need to do is post from Instagram to Tumblr - so setup a Tumblr account - then every time you add to tumblr - IFTTT will tweet that photo with caption as tweet text
If
New photo post
This Trigger fires every time you create a new photo post on your public Tumblr blog.
Then
Post a tweet with image
This Action will post a new tweet to your Twitter account with a linked pic.twitter.com image. NOTE: Please adhere to Twitter’s Rules and Terms of Service. Learn more
Discover more time saving integrations for Twitter and Tumblr (legacy)