Develop a website that buy and sell digital products

I need a website develop with the following:
- Integrate with Billplz (payment gateway)
- Allow seller to post their documents (winword and / or PDF).  They need to key in name of the prospect, contact details, commencement date, budget expectation (rm), the current cost per month (rm), any other cost (rm)
- buyer (only me) can verify their documents, if good documents, and things completed, i will make payment via billplz to seller
- for seller, they need to go through a verification process, seller to key in their name, ic, profession, linkedin profile connection, upload their profile (cv / resume).
- A schedule (calendar) appointment for meeting
- Seller can sign up using personal email or Linkedin
- Code verification via email - The Seller's email
- Buyer do part payment based on milestone achieved
- Allow Author to verify and subscribe on to the platform
- Buyer can choose the lowest bid and award the job to the successful Seller.
- Notification Message via email to me - Buyer after seller registered.
- Buyer can post a job, the name of the job, the target date to complete, the job cost
- I need API for other tracking system to integrate