Hello! I’m afraid it will not be in the installer options as the plugin is not yet fully developed or supported. But, you can try using the gem https://rubygems.org/gems/foreman_azure_rm with gem install foreman_azure_rm or directly clone it from the source. Although, I assume it might cause some breakage issues as it is dependent on fog-azure-rm-downgraded if you see https://github.com/theforeman/foreman_azure_rm/blob/master/foreman_azure_rm.gemspec#L16 whereas the latest fog-azure-rm is way too ahead of this in the upstream https://github.com/fog/fog-azure-rm. And since there is a version upgrade request to fog-azure-rm which is on hold, we are progressing with alternate approach to fully support foreman_azure_rm soon.
Still you can track the progress on Azure Plugin Missing/Broken?
Thanks! 
