Since this is a modified (mod) APK, it is not available on the Google Play Store . Use these steps to install it: Releases · Medard22/Dolphin-MMJR2-VBI - GitHub
It may include specialized configurations to better utilize Vulkan or OpenGL backends, which are critical for stable frame rates. How to Install Dolphin Black V2 APK
It is specifically optimized to provide smoother gameplay on older or less powerful smartphones that might struggle with the official app.