Integrate existing frontend template to our backend

I need the service to integrate our e-commerce backend to an existing front-end template bought on Themeforest.

Backend endpoints:
http://18.231.178.99:3000/document
Font-end template
https://themeforest.net/item/ciseco-shop-ecommerce-nextjs-template/44210635

Links to the pages needed

Homepage - https://ciseco-nextjs.vercel.app/ (Need to add Search bar on the header)
Register - https://ciseco-nextjs.vercel.app/signup
Login - https://ciseco-nextjs.vercel.app/login
Forgot password - https://ciseco-nextjs.vercel.app/forgot-pass
Account page - https://ciseco-nextjs.vercel.app/account
Favorites - https://ciseco-nextjs.vercel.app/account-savelists
Orders - https://ciseco-nextjs.vercel.app/account-order
Change passwords - https://ciseco-nextjs.vercel.app/account-password
Search results - https://ciseco-nextjs.vercel.app/search
Categories - https://ciseco-nextjs.vercel.app/collection-2
Product Details - ciseco-nextjs.vercel.app/product-detail (Need na extra customization on this page, instead of the Add to cart buttom it will be a Customize button, that will need to open a modal with an wizard screens so the user can choose the details of the products and in the end chose to upload the layout or to customize it using our web to print app. Details attached on PDF)
Cart - https://ciseco-nextjs.vercel.app/cart
Checkout - https://ciseco-nextjs.vercel.app/checkout