Powerpoint File Issues on new iPad... Please HELP?!?

I have a new iPad at my office. On the old iPad, I was able to send large powerpoint files by email from my Mac computer to the iPad. The iPad would open the presentations in Keynote... it worked just fine. We now have a new iPad (the old one is not ours anymore) and itwill not open large powerpoint files. Small files open fine. The large files say there is an error in Keynote and in the new Powerpoint app (that I paid a lot of money to be able to use..). Again this is just with presentations with more than about ten slides...

I have tried all of the solutions on other threads and on the web 😠 nothing works... I also checked the setup on how the old iPad was done... It is the same... I don't know what is wrong... But I am really frustrated 😠...Is there a setting I need to change? HELP!!!