Roadblocks allow you to serve multiple creatives together on the same page, however this only works on managed inventory where you can control both sell-side and buy-side options. For more information, please see: Microsoft Learn - Target Your Inventory with Roadblocking.
From an implementation point of view, there are no specific changes (it just requires all roadblock tags to be implemented on the same page) compared to the banner implementation so please follow the steps on the banner demo page to set up AST.
Finally, regularly checking on the AST release history is encouaged so that you can see the latest releases and adjust the code accordingly if needed (due to breaking changes, for example).