"An unexpected problem has occurred" using Adobe Express Embed SDK

I have the job of connecting Adobe Express Embed to a web application using Adobe Express Embed SDK. I have created a new Adobe account for this purpose but always get the error:

An unexpected problem has occurred. Try refreshing the page or return to the home page.
UUID: 604be501-1aea-4bcf-9c4f-9db5683be6b3

The UUID changes on every call. Looking in the browser's developer console I see a lot of errors (see attached log). Please assist to eliminate the errors when using the API.