If you see an “Unable to sign you in to your Apple Account” message
If you see this message after attempting to sign in on a new device or web browser, wait for at least 24 hours, then try to sign in again.
If you see a message that says “Unable to sign you in to your Apple Account. Try again later”, you’ve attempted to sign in to too many accounts on that device or web browser within a short period of time. You need to wait at least 24 hours before you attempt to sign in again on that device or web browser.
While there’s no way to shorten this waiting period, you can continue to use other devices that are already signed in to your Apple Account.
During this time, don’t:
Sign out of any of your devices
Reset your Apple Account password
Begin an account recovery request
Doing so won’t remove the message, and might further delay access to your account.