This is answered in the FAQ: https://www.nextscripts.com/faq/#privacy-security
I got email from Google (LinkedIn, Facebook) saying “Your account was accessed from some remote location”, was that you?
All our scripts are installed on your server and your server makes posts to your networks directly. When you make a post your server logins to your account on your behalf and makes a post. The location in the email that your account was accessed from is a location of your server.
Please confirm that it was you. It might take several times and then Facebook will stop asking.
Alternatively you can try to configure using session, not username/password or vise versa.