Urgent takeover of my account before I go away!

[AllAboutIrish]

Hi, I am in a dire situation....am about to head off to internet free land for a week first thing tomorrow morning. When I am gone I need to get a substitute to teach a class online for me. This person has used my log in details before to teach for me (I'm on Pro plan, with myself as the only user). This has worked fine - as I was on wifi and I would get a message on my phone to confirm his log in. So no problem!

But this time I will be away from wifi. What I thought that I would do was edit the email address on the account for the week - put his email address on the account instead of mine. I assumed that would be no problem. However, when I go to edit the email and input his email address I get a message that that email address is already taken and can proceed no further.

Then I thought I would upgrade and add him as a user for the week. But it is not at all clear to me how much this will cost, and if I would have to pay for him for a year. I literally only need him to use my zoom account for one hour! 

Completely stressed about this, and would be so grateful for any advice asap! Thank you!