It is not a difficult operation. All you have to do is enter the six-digit number displayed on the one-time password authentication app into the screen. However, if you find it difficult, "Authentication by email" is easier to use.
Please check the Expo ID Registration Manual on the Ticket Information page on the Expo 2025 Osaka, Kansai, Japan official website before registering.

ExpoID Registration Manual:
https://www.expo2025.or.jp/wp/wp-content/themes/expo2025orjp_2022/assets/pdf/tickets-index/id_registration_manual_en.pdf