Problem Deployment Kitty Items Heroku

Hi,

I’m trying to deploy Kitty Items in my new account of heroku with the [Kitty Items heroku buttom].
(https://dashboard.heroku.com/new?button-url=https%3A%2F%2Fgithub.com%2Fonflow%2Fkitty-items&template=https%3A%2F%2Fgithub.com%2Fonflow%2Fkitty-items)

(I have configured correctly the MINTER_ADDRESS and the MINTER_PRIVATE_KEY )

Always give me the same error in the first step (Configure environment):

There was an issue setting up your app environment.
** an unexpected error caused the job to fail*

Thank very much for your help.