I'm trying to send a PDF for signature via Dropbox Sign. It is rather large - 130 MB and 192 pages. I have already uploaded it to Dropbox. Every time I try to set it up to be sent for electronic signature, after I put in the name and email address of the signer, it gets stuck on the "Preparing documents..." page indefinitely. I tried on another browser that I never use, and the same thing happened. How can I get it to work? Does Dropbox Sign only work with small documents?