Hello everyone, does someone knows how can I connect my Matomo (before Piwik) to GrowthBook?

Instead of connecting directly to Matomo, you would connect GrowthBook to your MySQL database where you are storing the Matomo data

Thank you for the reply. I don't have DB to store Matomo data. I just have self hosted Matomo. You mean that DB or I need something more?

Yes, the db you are using for the self hosted Matomo