Do I need a card to start the trial?

No — the signup form takes no payment details on any plan, and on a monthly plan the button states the terms plainly: 15 days free, up to 1,000 orders, no card needed. Pick pay-as-you-go instead and you are asked to tick one acknowledgement rather than to pay: no monthly fee, charged per order, cancelled orders count, VAT on top. The card comes later, from Settings → Plan & billing, on Stripe's own page. Separately: your CUSTOMERS still never pay online — cash or card machine on delivery is the whole payment story on the ordering side.