Are you using the right account?
If you are seeing this error, you are using an account that applied for registration as a main institutional account. Each institution has only one of these accounts and they are usually (but not always) held by someone in the main international relations office. If this is your case, you are in the right place.
Otherwise, if you needed a personal account as an Erasmus coordinator, IRO member or otherwise responsible person (for example to review or sign an OLA) you may want to read the FAQ on how to get a staff account.
The "declined institution account" error message means that the account used to try logging in has not been verified yet. Confirming registrations has to be done manually to ensure that only actual, official institutions have access to the Erasmus Dashboard. Normally, this procedure takes less than a few days, but you may be experiencing temporary delays. However, you will receive an email notification as soon as your registration is confirmed.
Please also note that it is always worthwhile to check the spam folder in case the emails are landing there.