Adobe Sign stopped working

I have a single user account with Adobe Sign and recently the documents I've sent out for signature are received by the first person in the chain, but the body of the email looks different and they are not able to get access to the document to sign it and move it on to the next person in the chain.

Is there a limit to the number of times I can use Adobe Sign and have I possibly exceeded it - or is there a fault with my account?