Screensharing a Powerpoint on Zoom

Hi there, I need to do Zoom Presentation very soon. Keynote doesn't work so bought Office 365 to do Powerpoint but it doesn't work properly either. I want to share only to Powerpoint without my audience seeing my whole screen but can't. I have tried doing it with Presentation Mode and cropping to share only that part of the screen but none of my transitions work when i do it that way and I can't easily go back to me. Is buying a PC the only way round this? I have been told it is but thought I'd ask just in case. Already know a Tec person switch to PC because of this. Mac will lose a fair bit of business if this doesn't get sorted. The PC works like a dream on Zoom. I love my Mac and don't want to switch so hoping there is a way. Any suggestions?