This error is caused by a screen displayed by Instagram when logging into the account like this:
Unfortunately as you can see above, this means that Instagram has sent you an email to reset the password. You will need to reset your Instagram password, and then change the password we have stored (to the new password – see the steps at the bottom of this article) before we can post.
You will need to login to Instagram on your phone or tablet (sometimes the error won't appear on the web), and see if it gives you a verification screen like above. You should also receive an email asking you to reset the password. These emails can sometimes take 5-10 minutes to come through, and can appear in your spam box sometimes. The email looks like this, and is the same if you request to reset the password through the "forgot your password" feature:
Once you have changed the password, don't forget to change the password we have stored in Schedugram to the new password – see the steps at the bottom of this article – before we can post.
If you have any problems, just reach out to our team by logging a support ticket and we will be happy to assist.