To display Instagram feed on your blog you'll need to add your Instagram token to the 'Edit Theme' panel. The Instagram token is required so it can authorize Tumblr to access your photos.
If you don't know your token you will need to generate one. You can do this by clicking the generate link on this page http://instagram.safeasmilk.co/. After clicking, you'll be prompted to authorize access to your Instagram. You might be requested to enter your login credentials.
Once this is complete you will be redirected back to a web page on safeasmilk.co where your token will be visible. Now simply copy this token and paste it in your Edit theme page under "Instagram Token" field.