Do not give them a credit card number! They will charge you a fee for the paperwork, and give you the option to sign up for a bogus/useless monthly service that is in addition to the fee for the paperwork you already paid... even if you select and have PROOF that you did not select the monthly service, they will charge you anyway and REFUSE to provide a refund.
If you absolutely must use their service (because, it is in fact cheaper than hiring a lawyer), use a gift card w/only the amount that is needed for the paperwork. This process of signing you up for a monthly service is fishy and scammy. Go elsewhere or use a gift card if you must.