If you want to create a new FTP user for your developer then you can do this using in your Vesta web panel.
1. First, using your “admin” user log in to your Vesta panel.
user > yourwebuser > login as “webuser” > web > yourdomain.com > edit
3. Check “Additional FTP”
4. Provide the FTP user credentials and path.
5. Connect via FTP software