Hello,
you can’t use this plugin with a stable version. The changes for Foreman core has been merged today! So the first Foreman version that will work is 2.1. We don’t have any installation information yet, but generally speaking you only need Foreman 2.1 (or today’s nightly) and smart_proxy_ipam plugin to have the integration. Then, optionally, you can install foreman_ipam plugin to get the dashboard widget but it does not provide anything else IIRC, so it’s not crucial to have it.
In short, you are a bit too early but we would love to see you testing this. For little bit more info go here: