To register an Expo ID, go to the Expo ID login screen and click “Register for an account here”.

Expo ID login screen:
https://usrmng.accounts.expo2025.or.jp/idmng/users/screen/menuScreen 

Detailed instructions on how to set up your Expo ID can be found in the Expo ID registration manual, which can be found through the following link.

Expo ID registration manual:
https://www.expo2025.or.jp/wp/wp-content/themes/expo2025orjp_2022/assets/pdf/tickets-index/id_registration_manual_en.pdf 

If you live in Osaka Prefecture, support for registration is available at the support desk.
If you are not confident using a smartphone etc., tickets are also available to purchase on the day:
https://www.expo2025.or.jp/en/news/news-20250225-02/