In order to use environments, your Puppet masters will need to be configured to load manifests and modules relative to the requested environment.
This is the default behavior in Puppet 4+
This behavior is controled by the following settings (listed with their default values):
codedir = /etc/puppetlabs/code
environmentpath = $codedir/environments
basemodulepath = $codedir/modules:/opt/puppetlabs/puppet/share/modules
The environment requested by the agent or assigned to it by an ENC is looked
for at $environmentpath/$environment.
That environment may have an environment.conf file in its base directory that
specifies its own modulepath. If not, the default computed modulepath for that
environment is $environmentpath/$environment/modules:$basemodulepath.
These configuration variables are documented at Puppet Configuration Reference and their interaction in forming the modulepath is documented at Directories and the Modulepath. More information can be found about environments in general at Creating Environmnets.
The evolution to using environments in this way was a gradual one from community conventions to supported feature and there were several intermediate stages that had different configuration requirements within the puppet.conf. Some Puppet documentation from the 3.x and 4.x series may no longer be applicable to the above which solidified in Puppet 4.x.
If you need to upgrade away from any intermediate setup see Environments in Puppet 3.8 for examples that may help.