Develop an On-Line Commerce to sell an existing service

At the moment we (Company) are selling a service (to Consumers or Businesses entities) provided in form of a PDF report and paid via bank transfer. The entire process is currently mostly manual, and we want to transition to a fully-automated system.

The first step of this transition would be to automate some parts of the process, specifically the sign-up and the payment parts.

The process would be the following:
1) User sign-up using a dedicated page
2) User logs-in to the dedicated area
3) User decides which service to buy from a list of available ones
4) User agrees to Company's T&C and digitally signs the Contract
5) User can be charged immediately or when the service is ready to be delivered
6) User can follow the status of his request from a dedicated Control Panel
7) Company receives the request and manually uploads the Report, as well as the Invoice
8) User receives an e-mail and downloads the Report

API integrations:
- Contract signature: Docusign (www.docusign.com)
- Payment: Adyen or Stripe (next: Paypal, Sofort/Klarna)

Development Language:
- HTTPs
- PHP
- PostgreSQL
- Angular or React
- FTPs