I do appreciate your help.
Acturally, I already googled and read your solutions but I didn't know what they're saying exactly because the explanations were not fit to mine.
I couldn't find "Buy VIP & Points" button and no meaningful contents appreared when I clicked "Charge Kafra Points" - I mean Power-Up page in Worp Portal.
And I ignored things about "View > Settings > In-Game" options because I couldn't find those menues in every web page.
I just thought those informations are too old so not helpful now.
However, after reading your answer, exactly same solutions I read before,
I finally realized I have to use Steam Client App and log in there to use Steam Overlay - this makes steam users can transfer cash points in Steam Wallet to other games.
Many people says "log in in Steam first" but I logged in Steam web page.
Anyway, I solved my problem thanks to you.
It's sad to hear that I cannot move my all information about RO2 in Steam to Warp Portal.
I just want to play RO2 without being bothered by anything.
Edited by 3350160116140731193, 12 September 2018 - 06:14 AM.