I am not good at English, so please reply in easy-to-understand English.
https://developer.ebay.com/DevZone/sandboxuser/
I registered a sandbox on this site.
https://signin.sandbox.ebay.com/signin/s
I tried to sign in to the sandbox, but I couldn't.
For the password when signing in to the sandbox, I used the password when I registered in the sandbox. Why couldn't I sign in?