You will first need Busybox (free on GooglePlay)
- Root & Download this APK
- Install the app and launch it.
- Install TWRP over it and then close it over the taskbar.
- Reboot (to reboot from app restart app after install)
To boot into TWRP press the Volume Up Button several times at the Meizu logo, while it is turning on.
The download folder in TWRP is located under /data/media/0/download.