Since the launch of the Xbox One, we are still waiting for Microsoft to put in place the Xbox PC Store for the content of the latest console from Microsoft via Xbox.com. Indeed, if all games can be found on a specific section, this is not the case with other content such as downloadable content , demos etc. as is the case for the Xbox 360. It is therefore impossible to retrieve the content in question within through its console.
It seems that the American manufacturer is currently working on this problem , starting with Smartglass application. Indeed, as you can see in the picture below, the latest version of the beta Smartglass offers an option - not active at the moment - to acquire the content that interests you through the application. This could be particularly useful and interesting if it can start downloading away (to find the content in question already downloaded to your return home , for example)