Niffards answer is correct, however you should set up self custody wallet like exodus, and from coin base mark as sent to self, then send to exodus wallet address. From the wallet do your send to lb vendor. If you continually mark as send to self from cb and send to different vendor addresses this might eventually get flagged as suspicious on cb.

Just mark it as your own

It's definitely worth setting up a Wallet if you can - it's an extra step but it's one that basically makes you extra safe! Electrum is a nice easy one but there are loads out there - seemed like hassle to me at first but got used to it pretty quickly :)