I have this problem constantly. Looks like bad app design to me.
FROM GUEST:
Hi there! I received an email for the request for the $50 pet fee, but when I followed the link it just brought me to the air bnb home page. I'd like to submit payment ASAP so if you can direct me, that would be appreciated!
FROM AIRBNB:
Could you ask them to go to this link on a computer or browser to find where to make the payment.
<LINK NOT SUPPORTED>
If they are using the app, they may need to log out if they are going to use a mobile browser or it may revert to the app by default and not stay on the website.
The problem is 70/80% of customers use the app. And when they go from email to the link it defaults to their device and it's impossible for them to find out how to pay.
It's designed to be paid on a browser. So if they use a computer it's preferable.