First thing the 60% revenue means that for every $1 of advertisement that you earn on your videos, then you get 60% of this (so in this example 60 cents). Second you shouldn't need to worry about a catch up payment just yet, though one thing I wanted to check with you, just because you are seeing that message when you hover over the 'I' on the catch-up payment is that have you linked your paypal email address to your Freedom account??
As the message would see to suggest you haven't done this. If you could check on your Freedom account, basically log in and go to your profile, you should see the box for paypal email address at the top of the page, if this is filled in and is correct, and all the details are up to date then you don't need to worry about anything.
If you have any more issues or queries please don't hesitate to ask