You can install Moodle manually on any of your domain using the below steps.
1. First, you need to download the latest stable Moodle installation package from below link.
2. Then, please upload the package under your public (httpdocs) directory, which is the main one for the web site content. If you decide to use the script in a sub directory of the main one, place it there.
You can upload the Moodle package either through Plesk -> File Manager or using an FTP client.
After this you need to create a new database and add an user to it. Once the database is created and the package is uploaded, please extract the Moodle archive through File Manager.