50 customers ? You can build it with Django and sqlite with zero dependencies and deploy via scp, run it on the cheapest DO and call it a day. Easy to scale later too and you will be developing/deploying the business logic from day 1
Rent a cheap VPS on Hetzner and self host this stuff. Use Cloudflare R2 instead of S3 for storage (Egress is free). Use SQLite for the DB (would easily support 50 people!). If you add a dependency truly ask yourself why you need it. That is unnecessary operational and financial overhead IMO.