It is asking for a passphrase
The sender set one. We do not have it and cannot reset it.
Where it comes from
The sender chose it and should send it to you another way - a call, a different app, in person. That is the point: the link alone is not enough.
Attempts are limited
After ten wrong attempts the secret locks permanently and the sender is notified. A wrong attempt never uses up one of your views.
Still stuck? Contact support, or send a secret of your own.