From TianoCore.org:
"[TianoCore is the] community supporting an open source implementation of the Unified Extensible Firmware Interface (UEFI). EDK II is a modern, feature-rich, cross-platform firmware development environment for the UEFI and UEFI Platform Initialization (PI) specifications. We hope that you’ll review our wiki documentation, use TianoCore for platform firmware, report any issues you find, and contribute to the community."
You can install and run EDK II UEFI on some platforms as part of the reference software stacks shipped with the Arm Reference Platforms deliverables.
Alternatively, follow the official getting started guide.