Zoom app

I've been a long time zoom user as a teacher. I set up lessons one-on-one and have since the pandemic. No problems. Used it yesterday, twice, no problems. Today clicked on my zoom app to set up a lesson and got a screen that said set up an account and download Zoom! I have zoom downloaded. Could not reach anyone at customer service. I do have a pro account. I tried to re-set up an account said you already have an account and then said download new version. I don't have Wi-Fi so will have to go tomorrow and use a free Wi-Fi at library. Any advice or hints when I go to library?  Will downloading the new version make a difference? Why could I use it yesterday and not today? Any help or answers I would greatly appreciate! Thank you very very much.