Purchase Final Cut Pro for iPad ($4.99/month) and use Universal Control to edit between iPad and Mac. Not the same as native Mac FCP, but a legal low-cost entry.
Here is the correct workflow for a professional editor: finalcutpro10812dmg work
If you have acquired a finalcutpro10812dmg (or similar) file from a third-party website (not the official App Store), please consider the following critical warnings: Purchase Final Cut Pro for iPad ($4