You can follow the video bellow for vintage themes or 2.0 themes or follow the tutorial.
Access this link
Video for vintage themes
https://www.youtube.com/embed/UCkfBHhSczs
Video for themes 2.0
Click or press on "Add app" and proceed to install the application.
After the installation you will be redirect to the app dashboard, now you have to connect your instagram account, so click on the button "Connect an Instagram Account".
You will be redirect to Instagram, if you are already logged in, you only need to approve the application, but if you are logged out, you have to log in in your account.
Click on the blue button like the foto bellow.
After that you will be redirect again to the dashboard page, you can preview how your feed you be, clicking on "Preview".