Stratux is an open-source, non-commercial product, akin to a hobby. There is no formal documentation or customer support for it.
Some small companies exist that build commercial ADSB devices based on the Stratux project. There are varying levels of customer support from those companies, but I don't have personal experience with any of them.
The two places I have found answers to questions I had are the Stratux subreddit and the Stratux Github "Issues" tab:
Use Reddit to connect with other Stratux users (and sometimes developers, too) who might have already run across what you're experiencing (use the search feature before starting a new thread). You can also search Github to look for info on your issue.
If after talking to folks on Reddit it appears you have a new problem, you can try opening an issue on Github, which will get the attention of the developers. Use this sparingly and carefully, as if you are not crystal clear with your issue, or post about issues already addressed elsewhere, you will likely not get a favorable response, and might lose credibility with the devs that could hamper your attempts to interact with them in the future.
There is also a realtime Slack chat channel: https://stratuxadsb.slack.com/ . I have not tried to use this method, but theoretically you could go there to talk in real-time to folks knowledgable about Stratux.