WordPress Multisite refers to a single WordPress installation configured to manage several separate themes/sites typically linked to a subdomain or other domain. If you simply need multiple Hosted domains/installs, you may add additional domains/sites to your current Hosted plan from your Hosted Dashboard by clicking Add Site under "Plan".
If you are looking to create a WordPress Multisite or SaaS webste using WordPress, unfortunately our current infrastructure is not setup to allow Multisite configurations.
Each Envato Hosted account is given a set amount of webspace, memory and bandwidth tailored for a single WordPress/ Theme install and domain. WordPress Multisite requires more memory, space and sub-domain support than these accounts can provide.
We are looking to offer a Multisite option in the future. For now, we recommend looking into one of our excellent hosting partners for multi-site options: https://themeforest.net/get_hosting