A first-party Wavedash SDK for Unreal is not yet available — we're actively working on a web target for Unreal. Until that ships, Unreal's stock HTML5 export (deprecated after 4.23) and third-party web packagers are the only way to get an Unreal game running in the browser, and Wavedash can host whatever static output they produce.
If you already have an Unreal project exporting to the web today, you can integrate by calling the JavaScript SDK from your HTML shell the same way the custom engine guide describes. We're happy to help thread Wavedash calls through whatever bridge your exporter uses — reach out on Discord if you want to compare notes or get early access to the Unreal target as it lands.