AWS API Gateway guide: There was an error processing the login.

Completely new to auth0 so perhaps cannot ask the question properly, my apologies.

I’m trying to configure AWS API GateWay test application as described here.
All previous parts were configured successfully (as far as I can test).

I have uploaded the static website to S3 and the login form displayed properly. I have added user to Username-Password-Authentication and can see him in my auth0 account. Allowed Origins set to

Next the manual assumes I should be able to log in using the email and password which were set to that user in Username-Password-Authentication. In fact I cannot, the error message is There was an error processing the login.

The only moment I’m not clear about is: in the part 2 we edit inline policy for auth0-api-role and

To enable access to the API methods
for this role, apply the following
policy after updating the ARN with the
one for your API.

I’m unsure which ARN was meant here and used ARN like arn:aws:execute-api:us-east-1:111111111111:78aaa32ut9/*taken and stripped /GET/pets from the end of ARN of API GW Method Request

How can I troubleshoot it? Could anyone advise, please?