CBR.WinRT for Windows 8, as all Windows Store applications is available only through the store. Find below a link the web store and (if you are under Windows 8) a direct access to the Store application
Link to the web store, where you have CBR description
Only if you are under Windows 8, directly open the store on CBR
CBR.WinRT is available for free during a trial period of 15 days. Then, to support the project, you can buy it at the lowest price of the Windows Store.