Tips for getting waitlist signups

Hi, I have recently started a process of creating my app where you can find friends to go to concerts with. We are going to launch in the Netherlands first. I am currently creating on Instagram and TikTok, and I am collecting waitlist signups before launch, so that we can send out emails when the product launches. I got some people from my posts and videos, but the process has been slower than I hoped.

I feel like most step-by-step guides that I see are made for individual creators. I was wondering if anyone could give me a guide of how to grow as a brand. I do not have experience with this and I am a bit clueless! Thanks!