You can post a Show HN here so people could see your product.
You can have a blog in your product's website and use your content and digital marketing product to do content and digital marketing.
You can search for digital marketing agencies and talk with them.
You can contact companies that do content and digital marketing (who doesn't?) and talk with them.
You can search on LinkedIn for people with that profile and reach out.
You can look up subreddits.
If the app doesn't solve a problem someone has, that's a problem.
If you can't find people with the problem the app solves, that's also a problem, but a different one.
If you built something but aren't sure it solves anyone's problem, that's a third type of problem.
Anyway, the best way to get organic users is to talk to people about their actual problems and build something that solves them.
Good luck.
My product is a writing tool based on GPT3 technology, so the target audience is content and digital marketers, and I'm having difficulty getting this audience internationally.