TWRP is now available for download for the Samsung Galaxy Note 5 that allows users to download and flash custom firmware and various kinds of hacks onto the phone. TWRP is a custom recovery that replaces the stock recovery on Note 5. Stock recovery does not allow user to flash any modifications or custom firmware.
TWRP is made by developers at XDA and is free to download. You can download it from following link and flash it using ODIN.
Only after successful install of TWRP on the Note 5, any kind of third party installation is possible. Keep in mind that this will not give you root on the phone.