As per your steps installed SCCM installed in server 2012R2 all the client pc's i can visible, but in client pc's push installation setup is not installing.
i have followed below steps.
I have checked below link also.,
www.prajwaldesai.com

Kindly check the client installation failed logs.
i have followed below steps.
I have checked below link also.,

How To Install Configuration Manager Clients By Using Client Push
In this post we will see how to install Configuration Manager clients by using client push. After installing the configuration manager in


Kindly check the client installation failed logs.