Clicking the button on https://run.claw.cloud/ led to an endless cycle of selecting US East and naming my workspace, and then reauthorizing with GitHub, and then selecting my region and workspace name, and then reauthorizing with GitHub, ad infinitum.
The only way I was able to get in was by starting from an entirely different page, and authenticating through GitHub, and then coming back to that point. This is obviously very bad UX!