Stripe Onboarding Verification Automation Setup

We are looking for an experienced automation specialist to quickly implement a reliable onboarding workflow connecting Stripe, Make (Integromat), and Google Sheets.
This project is time-sensitive. We expect fast execution, and any bid submitted is considered a commitment to deliver within the agreed timeframe.

System Overview:
Payment Gateway: Stripe
Automation Platform: Make
Database: Google Sheets (already structured)
Email Provider: Infomaniak
Main Objective:
When a payment is successfully completed on Stripe, the system should:
Detect the payment
Retrieve customer data
Assign a postal box number (only for specific offers)
Store the client in Google Sheets
Send a personalized email with their postal address

Workflow Details:
Stripe Trigger (we provide account access)
Event: checkout.session.completed
Extract:
Customer email
Full name (first + last)
Product type (Starter or Domiciliation via metadata)
Conditional Logic (Router)

A. Starter Offer:
Retrieve the first available number from Google Sheets (status = FREE)
Mark it as USED immediately (to prevent duplication)
Assign it to the client
Save client data in "CLIENTS" sheet

B. Domiciliation Offer:
No number assignment
Save client directly in "CLIENTS" sheet
Google Sheets Structure (already set up):
Sheet "NUMBERS": pool of available postal box numbers
Sheet "CLIENTS": customer database

Email Automation:
Send a confirmation email via Infomaniak including:
Full postal address
Assigned number (if Starter)
Link to upload ID documents
Send to:
Customer
Admin (cc)
Business Logic Requirements:
Numbers must be assigned sequentially and never duplicated
The system must handle concurrent payments safely (important)
Only confirmed Stripe payments should trigger the workflow
Deadline & Commitment:
Project must be delivered quickly (please specify your timeline when bidding)
Only apply if you can start immediately
Your bid is a commitment to deliver — no delays, no scope drift
Expected Deliverables:
Fully functional Make scenario
Clean and maintainable structure
Proper error handling
Short documentation or walkthrough
Ideal Profile:
Strong experience with Make (Integromat)
Experience with Stripe integrations
Comfortable using Google Sheets as a database
Detail-oriented and reliable