Yes, as admin you can create user accounts and submit papers on behalf of the author.
1. Please check first whether the person already has an account in the list of users:
Overview => User and Participant Management => List of All Users.
Enter the name or email address in the search box to see whether the user exists.
2. If there is no account listed, please click on Create "New User Account" on this page:
Overview => User and Participant Management
Please note that you cannot set the role "author" as it will be set automatically when the paper has been submitted.
Click on "Submit and Begin With Submission of a Contribution" to submit the paper as next step.