The .7z extension indicates the file is compressed using 7-Zip , a common high-compression format used in the emulation community to keep file sizes small. Context of the 5.0 Era EmuCR - Emulator News & Download (EmuCR.Com)
The primary focus of build 5.0-17620 was a significant update to the .
These builds are often compiled directly from the latest source code (Git) to give users access to the newest features before they reach a stable release.
Dolphin version is a specific development build of the Dolphin Emulator , a popular open-source software for playing GameCube and Wii games on modern systems. Key Technical Change: Vulkan Descriptor Overhaul
The term in the filename refers to EmuCR.com , a website that provides custom-compiled "nightly" or "development" versions of various emulators.