Complete Sendy Installation fix 404 error

I need a skilled freelancer to help me quickly install Sendy, an email marketing software, on my server. I already uploaded the Sendy folder and added SQL but I'm getting a 404 error and need someone to successfully install and fix the error.

Key Requirements:
- Quick turnaround: I need this completed in an hour

Here's the guide: https://sendy.co/troubleshooting#404-error