Does your device already have a custom recovery (and/or an unlocked bootloader) installed?
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<br> The reason I ask this is it appears to me (someone will correct me if I'm wrong) that you need a custom recovery (like TWRP) and/or an unlocked bootloader in order to install Magisk and it suite of tools / functions (root being one of them).
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<br> So, it (Magisk) as well as SuperSU are not root exploits per se--i.e., they won't help you root your device or unlock your bootloader or install a custom recovery: you must have already found and used an exploit for your device that will allow you to root (install SuperSU) or unlock your bootloader (allows flashing a custom recovery) to flash the SuperSU or Magisk .zip package, etc.
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<br> Subtle distinctions, I know, but important ones...
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<br> (disclaimer: I don't really know anything about Lenovo devices, so I can't recommend any tools or methods to help you actually run an exploit that leads to root).