If you are specifically trying to run v0.27.1 over an older or newer install, use the "Support Tools" in the launcher to Clear Cache to prevent texture bugs.
Use a tool like VirusTotal on any .exe or .zip files before opening them. If you are specifically trying to run v0
Go to the "Repository" in the main menu to download new cars and maps safely. 3. Safety Warning for "Free" Downloads If you are specifically trying to run v0