What team is needed to develop an escrow service?

Question

Mobile development

There is no experience of serious development.
Escrow service involves the development of an application, interaction with payment systems and accounting tools for transport companies.
In addition, according to the plan, there are applications for smartphones for individuals.
I will be glad to any advice and offer of participation.

Answer 1

1) 1-2 developers per application
2) one team leader - an architect who sees the entire device
3) two backends (one with payments and architecture, the second with the API for interacting with applications and the site frontend)
4) two frontends (weaker and stronger) - you still have to make up, but harder - if you make interactive for PC and tablets.
5) tester. You can get by with one, even a chiropractor at the beginning.
6) support - calls and tickets when it starts, control over fixing bugs, reports to the team leader
7) and PM. It can either be divided between the team leader and the secretary (correspond with the same secretaries for transport and other billing), or he is also the CEO