Go to the official Windows Server 2012 R2 download page.
During setup, you can choose between Server Core (headless, recommended) or Server with a GUI (full desktop experience). Download W2012R2 Server ISO
Minimum requirements include a 1.4 GHz 64-bit CPU, 512 MB RAM, and 32 GB disk space, though for production, at least 2 GB RAM and 50 GB disk space are recommended. Go to the official Windows Server 2012 R2 download page
You will need to sign in with a Microsoft account and fill out registration details. 512 MB RAM
Choose your preferred language and select the 64-bit ISO option.
(Hyper-V or VirtualBox)? How to convert an evaluation to a full version ? Windows Server 2012 R2 | Microsoft Evaluation Center