Only members of the Site-Admin Group can add Paid Add-ons or Applications to the instance
By using Confluence Apps Manager
Navigates to the "Find new apps" section in the Confluence administration
Type "banners for confluence" into the search field and hit the Enter key
Click app to view the details
On the app detail view, click on the Get app button
Click on the Get it now button in the new pop-up
A pop up will inform you that the installation is in progress
When completed, a Success popup will show on the bottom-left corner to inform you that the app has been successfully added
By using the Atlassian Marketplace listing
Open the Atlassian Marketplace listing for Banners for Confluence
On the app detail view, click on the Get it now button
A pop-up will appear asking you to Choose a site to install your app
Select the site
Click on Install app
Click on the Get it now button in the pop-up dialog
A pop up will inform you that the installation is in progress
When completed, a Success popup will show on the bottom-left corner to inform you that the app has been successfully added