To enable Marketplace for your system go to the System Settings in the System Admin Panel and check the Checkbox Enable Marketplace
To select what add-ons are visible in Marketplace check the Require add-on Approval checkbox. Add-ons retrieved from our public repository require approval by the key-user to allow installation in the system.
Go to Marketplace – Manage Add-ons and to Fetch add-ons from the set external add-on repository.
Optionally, you can activate the System Setting to automatically retrieve add-on updates to automate the manual retrieving of add-ons and add-on updates from the public marketplace.