So I follow your step by step work all the way but no migcik app downloaded the apk and it says not install and my phone not rooted
Your issue with this can be the factory binaries. The factory binary is a firmware used by Samsung for testing hardware and repairing software. Samsung phones in North America have been stuck with locked bootloaders for a long time.
Please note that any root method you have found has been aqquired most likely from an XDA Developer and is still, “in development”. That means it’s not finished yet and it’s highly unstable. That is my current understanding. However you may try one of these methods, https://eeflee.com/note-9-root/ after unlocking the OEM in the developer settings. Personally I would use the PC version of KingoRoot. If you want to research this, here you go. https://forum.xda-developers.com/galaxy-note-9/samsung-galaxy-note-9-snapdragon-roms-kernels-recoveries--other-development/root-t3927413