You must pass atleast one query parameter in the URL.
For Video Entry IDs use the ?VideoEntryId parameter.
e.g. {{ serverURL }}/?VideoEntryId={Video Flow Entry ID}
For Chat Entry IDs use the ?ChatEntryId parameter.
e.g. {{ serverURL }}/?ChatEntryId={Chat Flow Entry ID}
For Campaign mode, include some query parameters that match your campaign configuration
Use only one of the above three options. Do not combine multiple options from above.