I have similar problem. Need to get keynote onto USB Thumbdrive per an instructor and use later in live presentation. I have an iPad air and a PC. I have sent via Dropbox first in Keynote, then in PowerPoint but doesn't open to read so is worthless to transfer to thumbdrive. Instructor is using a MAC. Sent to her email from Ipad but she has old software and is having trouble opening. Any suggestions?