Check your installation method. Make sure you're following the guide for the platform you're actually using. Modrinth and CurseForge each have different installation processes.
Make sure you downloaded the complete ZIP. The CurseForge version is distributed as a single ZIP archive. Do not extract, rename, or modify the contents before importing it into CurseForge.
Make sure you're using the correct version. Check the STARSOUL website for the currently supported release of the CurseForge pack.
Let the installation finish completely. Missing or partially downloaded files can prevent the instance from launching correctly.
Verify the server address. The STARSOUL server address is starsoul.industries.
Still having issues? Because this is an experimental CurseForge distribution, some issues may be specific to CurseForge. If possible, try the Modrinth version before troubleshooting further.