@dellenc  Can you check if sandbox are added to product profile in the admin console?   It is mandatory to have that sandbox added to their product profile in the admin console in order to start using the sandbox. 

@dellenc : Can you share what exactly happens, when you create sandbox, what success message you receive? Are you able to create sandbox, because sandbox creation need write permissions.

@winstonl3651471 That's great. Can you post the solution here, it would be community help for others who struck at same problem.

@winstonl3651471 Can you try configuring web SDK using information from  https://experienceleague.adobe.com/docs/experience-platform/edge/fundamentals/configuring-the-sdk.html?lang=en