It will help your scores only if they remove the delinquency after you pay, so you may want to try to negotiate a “Pay for Delete” with them, it’s only a $100 so it’s definitely worth it. This will bring your scores up and improve your chances of being approved for better cards.
If you just pay and the delinquency is updated as “Paid” on your report, it will not help your score but it will help your chances of being approved for a loan if a lender is looking at your report. In any case, it’s better to pay it off, but again, it’s better to get rid of it altogether.
I haven’t heard much about Credit One, just that they offer cards for people who are rebuilding and that they charge annual fees. If you treat it right you should be able to get your scores up with pretty much any card that reports to the Credit Bureaus.
Did you get the card yet? Can you close it before it reports if you get approved for the CapOne card you want? Might be an option to look at.