Hi! 

I would like to connect otree Hub with Heroku. I have the subscription: server deployment: Standard.

As I tried to connect I got this message: 
"This Heroku account is not verified. Before using oTree Hub, you need to verify your Heroku account by adding a credit card. This will allow you to provision add-ons and dynos."

So now I am wondering why I have to connect my credit card as I do not want to buy any add-ons? I do not see why I have to provide my credit card details for verification.

Thank you very much for any suggestions!

add-ons includes your postgres database. and you need dynos. without that you can't launch a site.