@Julie1824 I can understand the guests' discomfort with anyone coming in due to COVID, and hopefully they aren't just using that as an excuse. Not to mention it isn't safe for you to enter, either, due to COVID.
But apart from that, your approach wasn't the best. Saying you want to check on the property can make guests feel spied upon, and they aren't trusted, even if they have nothing nefarious planned and are respectful of the places they stay.
It's far better to state in your listing that you come by to do a quick clean and leave bedding and towels changes on any bookings longer than 2 weeks, and not give the guests a choice, just say it's how you run your business, and if they don't like the idea, they are free to cancel. You can't spring coming over on them after they've booked if you haven't made it a condition of booking your listing.
Do you have outdoor cameras so you can monitor who is going in and out, in case they are planning on having more people stay than booked for or have snuck in a pet? If so, I wouldn't be too concerned and would agree to the Zoom call for this booking, and change things a bit for any long term bookings going forward.