thanks for you question
So there are 2 points:
1. it seems that you did not load your credentials to use OpenStack api by using the openrc file. this is specify in the guide by running:
. <project>-openrc.sh
2. on the heat cli, you should only specify the key name, not specifying the key itself
BTW, as I saw, you are currently reading the develop branch of the PNDA guide, I would recommend staying on master branch which is currently the latest stable version (3.4)