Can my customers pay directly on my white label portal with their own card?

Yes, your customers can pay directly on your white label portal with their own card, as long as you have a payment gateway connected to it. The portal itself does not hold the money. It passes the payment to the gateway you have signed up with, and the gateway settles the funds into your own bank account on its usual cycle.

Getting that gateway account is the part that sits with you rather than with the portal. You apply to a payment provider in your own country, they check your business documents and your website, and once they approve you they give you the keys that are entered into your portal settings. After that the payment screen carries your own brand and the traveller never sees anyone else in the transaction. Most portals can hold more than one gateway, which is useful if you sell in different countries or want a backup when one provider is down.

There are a few honest limits. Card payments carry a fee charged by the gateway, and refunds, chargebacks and settlement timing all follow that provider rules, not the portal rules. Some suppliers also need to be paid from a deposit or credit account that you keep with them, so the money reaching your bank and the money leaving for the supplier can move on different days. Which gateways you can connect depends on your plan and on what is supported in your market.

Before you go live, speak to a payment provider that serves your country, ask them what documents they need and what they charge, and then run a small live test booking to confirm the money lands where you expect.