Your organization might require you to authenticate to MOVEit with an SSL (X.509) client certificate (client cert). This is common when two-factor authentication is required.
How you do this depends on your browser and how your organization has set up authentication.
Your organization can tell you which types of client certs it accepts for authorization, and will provide a way for you to obtain the cert.
Follow the instructions your organization provides, and/or the prompts presented by your browser. If your certificate uses a private key on the client cert that is password-protected, you might also be prompted to enter a password