Alright, so another try is in the OP.
Basically what is going on is described here: https://github.com/topjohnwu/Magisk/issues/2109 . 10 has new place for some binaries, both twrp & magisk have issues using them during flashing. Twrp temporary fix is in the latest update, as of the magisk - you can try downloading and flashing Q fix in recovery & then trying to flash the mod with magisk after reboot (report if that'll work).
! IMPORTANT NOTICE !
Mod is provided as is.
If you experience crackling noises during speaker playback - lower the volume, or stop using this mod.
I made everything to make it as safe as possible, but any modifications performed for speaker might decrease its lifespan.
You have been warned. I'm not responsible for any damage that might occur to your device.
09.09.2021 - mmtex canary magisk support 05.11 - Some props fixes - ACDB updated - Volumekeys addon upd 27.03 - MMT-EX installer support for magisk 20.4 04.03 - MMT-EX installer - aml support update 03.01 - Unity installer v5 update 24.12 - Further fixes for 10 environment support 15.12 - Installation fixes for 10 support 05.11 - Critical fixes 04.11 - Critical bootloop fixes - Overhaul to modular installer - Stereo playback for notifications - Voice messages recording fix