MCreator issue tracker has been migrated to GitHub.
Existing tickets have been migrated to GitHub. Please open new tickets on the GitHub tracker instead. If you do not have a GitHub account, all feature requests and bug reports from MCreator forums are still considered and checked by the maintainers.
MCreator has its own Java. Try running it with mcreator.bat so see the actual error log.
It could be that your antivirus prevented form extracting all needed files. Try disabling it and reinstalling MCreator.