Embed in Flask not working

Hi All,

I've gone through the steps here:https://docs.microsoft.com/en-us/power-bi/developer/embedded/embed-sample-for-customers#embedding-for-your-customers

And have delegated permissions as well. I've followed the config files in the github here:https://github.com/microsoft/PowerBI-Developer-Samples

but am still getting this error:

Error Details:
Error while retrieving report Embed URL

Does anyone have any idea what to do to fix this? I have a PBI Pro lisence as well.