Not able to access an agreement or an envelope

I have had several people who were not able to access a DS agreement that I sent at all. She tried 3 different browsers, cleared cookies/cache etc.  Does anyone have any idea why this happens and what I might be able to do to fix this?  The first 2 signers in my organization were able to sign and when it gets to the third one - not in my organization she could not get to the document.  I double checked the email it was correct and she was using a computer and not on a phone.  I don’t want to make my first 2 signers sign again as they are executives and it is a bad look.  Is there another way around this?