Hey Jmodeste,
It appears that you're wanting to purchase an iPhone and an Apple Watch from the Apple Online Store and use your MasterCard to make the purchase with monthly installments. We're glad to glad to provide assistance.
iPhone - Where to buy in Trinidad & Tobago - Apple -- Since Trinidad & Tobago isn't able to order an iPhone directly from the Apple Online Store, you'll need to pose your question to a bmobile Store or an Apple Authorized Reseller.
How to apply for Apple Card - Apple Support -- Also, you can purchase an Apple Watch through the Apple Online Store, but in order to pay over time instead of the full amount when purchased, you’d need to use the Apple Card. These are the requirements to apply:
"See if you're eligible
- To be eligible to apply for Apple Card, you must be 18 years old or older, depending on where you live.
- You must be a U.S. citizen or a lawful resident with a valid, physical U.S. address that's not a P.O. Box. You can also use a military address.
- Your device must be compatible with Apple Pay. See which devices are compatible with Apple Pay. Make sure that your device has the latest version of iOS, watchOS, or macOS.
- You must sign in on your device with your Apple ID and use two-factor authentication.
- If you have a freeze on your credit report, you need to temporarily lift the freeze to apply for Apple Card. Learn how to lift your credit freeze.
- You might need to verify your identity with a Driver License or State-issued photo ID."
All the best.