I have uploaded documents to FYI and when I try to send these for signature, the following message displays "Error posting envelope to Annature: Documents exceed maximum allowed size of 30mb".
The total file size of the documents you are trying to send for signature exceeds the limit.
Check the size of the PDFs you are trying to send to see which are large file (you can export the files to check the size in Windows Explorer).
It is likely there are images in one or more of the large them which is making the size bigger than usual.
You can remove any images that are not needed.
You can also use a tool to reduce the size of the PDF file size (refer to this wikihow article https://www.wikihow.com/Reduce-PDF-File-Size for information).