Because the official Dolphin project no longer distributes 32-bit APKs, any such file you find online is either:
Q: What are the system requirements for Dolphin Emulator 32 Bits Android Apk? A: The emulator requires a 32-bit Android device with a minimum of 2 GB RAM and OpenGL ES 3.0 support. i--- Dolphin Emulator 32 Bits Android Apk
If you are determined to try it on an older device, you must look for archive versions: Internet Archive: Some users have uploaded legacy files such as Dolphin for 32-bit phone Dolphin Dev Builds: Because the official Dolphin project no longer distributes