If you were able to login and complete onboarding through the Onboarding Portal, then the same email & password will grant you access to the Vendor Portal.
If you are a new user, you will need to be invited to the platform by your account administrator. If you don't know who your account administrator is, please contact us at support@revcascade.com and we'll be happy to assist.
If you think you have a login, but are not sure, you can always reset your password here.