The email confirming your account information was sent to you when you finished registering your account.
Depending on the settings of your mail service or mail software, emails from Reallyenglish may have been automatically put into a folder such as 'Spam' or 'Trash' etc.
Please check these folders and your mail settings and allow receiving emails from support@reallyenglish.jp.

Passwords must satisfy some rules (for example, 'must include both letters and numbers', and so on).
If your password does not satisfy the rules, you will see an error message in the top part of the page.
Check the error message to find out the problem with your password, and input a new password that satisfies the rules.