I assume you want to install the BR client on a client / end-user machine.
If that is the case, you can find the BR Add-In from the options available at the application access point. Just go to the application access point from the end-user machine where you want the add-in installed.
Please use Internet Explorer for this, since other browsers may have issues for the ClickOnce installation.
Choose Add-Ons from this page
From there you will find options to install the BR Add-In. Either the MSI option or the ClickOnce option is suitable for an end-user machine (You might need to install the pre-requisites if you are installing the ClickOnce version)
Remember, after you have set this up, the BR client will be available in your Programmes. You do not need to set up the Add-In separately in Excel as a COM Add-In, but can directly start it from the shortcut or the list of programs on the start menu