I want to buy a MacBook In installments

In the US, this program is available using Barclays Bank, a US unit of a British bank. There is another to apply for an Apple Card, through JPMorgan, a US Bank:

https://www.apple.com/shop/browse/financing

with Barclays, you get interest free financing PROVIDED you make every payment on time and complete all payments before the end date,. If you miss anything, you pay around 20 percent interest retroactive to the original purchase date.

with the Apple Card, you get 3 percent cash back, but I did not see any references to special financing. You pay their standard rate from day 1 for as long as you carry a balance.