User isn't redirected to signing

Dear community.

I have created an envelope, as I usually do, and added recipients to sign a document. One recipient receives the email with the link to DocuSign to sign the document, but when he opens it, he is redirected to a login page instead of the document itself. This happens only to this specific recipient. Other recipients do not have this problem.

Does anyone know what might be causing this behavior and how to fix it?

Thank you.