This is supposed to work, but since I already have an account it takes me to a different page.
https://my.roku.com/signup/nocc
But you already have a Roku account, or you wouldn't be able to post here. I don't recall any question about a credit card when adding a new device to my account. And while I did use a CC when I created my account years ago, it's since expired and Roku has never challenged me to update my info.
Dan
Roku Stick (3600), Ultra (4640), Ultra (4670), Ultra (4800), Premiere (3920), Insignia 720p Roku TV, Sharp 4K Roku TV, Nvidia Shield, Windows 10 Pro x64 running Serviio and Plex on a wired Gigabit network.