Do not download ARMv7 or x86 versions for a modern phone. They will either fail to install or force your CPU into 32-bit emulation mode, killing performance.
zip file, which includes the Armv8 Neon codec, from the following reputable sources: Free-Codecs : Offers the MX Player Custom Codec 1.49.0 r2 Mx Player Custom Codec 1.49 0 Armv8 Neon
make clean make -j8 make install
Mx Player Custom Codec 1.49 0 Armv8 Neon - Unlocking Enhanced Video Playback Do not download ARMv7 or x86 versions for a modern phone