The product is ready, but there is no marketing budget ,a classic early-stage situation. Paid traffic burns through cash way too fast and often with zero results.
Instead of trying to pitch your SaaS to everyone, shift your focus. Look for people who are currently struggling with the exact problem your product solves, and try to help them. People don't need another piece of software; they need a solution to their pain.
There are plenty of social networks out there, but in my opinion, Reddit is a great fit for most projects, and the traffic there is massive. It's the perfect platform where people discuss their challenges and look for the right tools every day.
Monitoring relevant topics manually takes way too long. There is a great free tool on GitHub for this called RedSignal. It automates the process by tracking keyword mentions and finding the exact people who need your solution right now. I suggest starting with that.
I am not going to teach you how to communicate with your customers. Some people jump straight into DMs, others prefer dropping helpful advice in the comments. Only you know your customers, so use whatever approach you think works best.
What free channels have you used to find your first customers?
Finding people with the problem is only half the equation. I'd also keep validating why they haven't solved it already. The first customers usually appear where the cost of staying with the current solution has become higher than the cost of switching to yours.