I stumbled into this problem while trying to install BusyBox. I have a OnePlus 7 pro with LineageOS 16 (rooted). But the solution might work for other devices as well.

Solution:

• enable ADB root access on your phone
• connect phone to your computer
• type the following into your cmd window

adb root
adb disable-verity
adb remount

• install BusyBox to e.g. /system/xbin
• (optional) revert changes

adb enable-verity
adb remount

Have fun!