Schedule your Instagram stories via direct publishing
Now you can publish your Instagram stories with a direct publishing option. Here are some guidelines to help you understand how to publish posts through Content Studio.
But you can still use the push notification method:
1- Login to your ContentStudio account.
2- Hover over 'Composer' in the navigation bar and select 'Social post' from the drop menu.
3- Now select your Instagram account from the left panel.
4- Once you selected the account, compose your post by adding your content, image, or video
5- Select the publish as and post type options from Instagram settings.
- Only one image or video should be included in the post.
- The duration of any video content should fall within the range of 4 to 60 seconds. It is recommended to maintain an aspect ratio of 9:16.
6- Now select the scheduling option and click on a post now. 
7- That's all your stories will post on the selected Instagram account.