I got my first 10 paying users from a simple email popup : here's the full funnel?

A few weeks ago I launched SkillVault (https://skillvault.fr) — a free certification prep platform in French covering 12 digital certifications (Google Ads, AWS, Meta, HubSpot, Salesforce, Power BI, etc.).
I had zero audience, zero budget, zero followers. Here's what happened.
The stack (under 10€/month)
Pure HTML/CSS/JS, no framework. Supabase for auth and database (free tier). Stripe for payments. n8n on a 5€/month Hetzner VPS for webhooks. Brevo for email nurturing (free tier, 300 emails/day).
The funnel that actually converted
Visitor lands on a revision sheet (free, full content, good for SEO) → after 40 seconds, a clean email popup appears → they sign up → Brevo nurturing sequence kicks in (3 emails over 14 days: value, engagement, then conversion) → they hit the paywall on quiz corrections and flashcards → they buy Pro.
Two people went through this exact flow and paid 7€/month each. My first recurring revenue ever.
What I learned

The popup timing matters more than the copy. 15 seconds was too aggressive (Google flagged it). 40 seconds + exit intent on desktop works. People have time to see the free content is legit before the popup asks for an email.
Give away your best content for free. My revision sheets are 600-850 lines of detailed HTML completely free, no gate. That's what ranks in Google and builds trust. The paywall only hits on quiz corrections and flashcards the "I want more" moment.
French market is a blue ocean. English certification prep is insanely competitive. French has the same demand with almost no supply. My SEMrush revision page got 235 Google impressions in 2 weeks with zero backlinks.
The nurturing sequence does the selling, not the site. Nobody buys on first visit. The 3-email sequence (day 3: tips, day 7: study method, day 14: here's what Pro unlocks) is what converts.

Current numbers

47 pages indexed in Google
~1500 impressions/2 weeks, ~120 organic clicks
40+ email signups
10 paying users (70€/month MRR)
Infra cost: ~5€/month

It's tiny. But the unit economics work and the funnel is proven end-to-end. Now it's a traffic game.
What's next
More SEO content (blog articles targeting specific certification keywords in French), Reddit/Facebook community engagement, and I just set up a LinkedIn company page. No paid ads — the margins don't support it yet at this scale.
If anyone has experience scaling a content/SEO-driven freemium product, I'd love to hear what worked for you.