Size And Download Issues

I'm experimenting with a trial version and haven't found an answer to this elsewhere.

I would like commercial clients to download a completed job in one batch but am encountering a size error.

• I created a photo product (downloads at 4000px, plus low-res) 
• I created a test gallery 
• I uploaded 205 jpgs to the gallery, saved at 4000px at 80 quality, which was about 550Mb in size.
• Watermarks were off.
• I created a test "client".

Clicking "download all photos" produced an error message saying that the zip file would be greater than 4Gb and therefore too big.  

After unsuccessful attempts to fix it I started again and uploaded 50 images.  This worked - but it did say that the zip file would be about 1.05Gb.  I continued and the end result was a folder 120Mb in size.

Is there some obscure setting that I've missed that makes the initial zip file calculation so enormous?

It is totalling the size of the original size uploaded of all of the photos. And technically it can't produce one over 4gb. I have plans on making it split into multiple zip files at some point.