Enable the USB Debugging and Developer Options on your MIUI device.
You may reach any error at the time of installing custom recovery about install drivers you have to download and install drivers for your LG K8 LTE LG-K350 mm1vn in your PC. On the installation, you have a choice to install USB drivers, so you can install drivers at the right time. Download and Install the ADB Fastboot drivers on your PC.Make a full backup of your devicewhich allows you to recover in case of problems.There should be 90% battery charge on yourLG K8 LTE LG-K350 mm1vn to perform the TWRP installation process.