Since the real Synapse X no longer exists, any "download" you find now is a fake file designed to steal your passwords or Roblox account.
If you are looking to learn about scripting or game modification, consider these legitimate paths: synapse-x-cracked-roblox-executor-full-download-crackgreen
These files often contain "loggers" that send your saved browser passwords to hackers. Since the real Synapse X no longer exists,