Firstly, make sure you're using Odin v184.108.40.206. Then turn off auto-reboot from odin options. after that plugin your device and insert the twrp file in ap. when the file have been passed in odin press the download mode combination on your phone as soon as the screen goes black change to the recovery mode combination otherwise it'll just boot back into system and twrp won't be installed.
You know what's funny? That your requested CSC is already included since V1.0
Always, if you upload them here (the oreo version)
I only support s8 based roms, if it works on s9 ported roms? Try it out with a backup, always the best to do
dd if=/data/media/0/EFSBackup/efs.img of=/dev/block/sda3 bs=4096