How did you grow/find your first group of users to a MVP product you just launched?

I'm a junior product marketer looking for advice. My team and I just launched a service called RoundUp, which is a free Chrome extension made for HR professionals. It's like a memopad that pops open inside Google Meet, where they can fill out candidate reviews once the interview is over - and it automatically links to a Dashboard, where HR folks can see everything in one place. It's got very basic features (so a MVP) and of course there are many things we need to get to. I'm new to doing product marketing and would love some advice from those who's gone through this phase of trying to grow the userbase from a grassroots perspective. What was the best way to get users on your site/product/service at the beginning? Were people willing to give you feedback and advice? (How did you find them?) Would love to hear your stories/kind advice!