First, log in to Plesk as useradmin, click on the ‘Domains‘ icon, and then select the domain you wish to add additional permissions to.
Next, click on ‘Web Hosting Settings‘.
Scroll down, and place a check mark next to ‘Additional write/modify permissions‘. You will receive a warning about this; click ‘OK‘, and ‘OK’ again at the bottom of the page.
Once receiving the confirmation that the command completed, your domain will have extra write/modify permissions for applications.
If you need any assistance with this process, or encounter any issues, please do not hesitate to contact our Technical Support Department.