To fix TurboTax installation issues with a license code, start by ensuring you're entering the 16-character code exactly as shown, including hyphens. Visit www.installturbotax.com with license code and sign in with your Intuit account. If the code is invalid, double-check for common errors like mistyped characters. Disable any antivirus software temporarily and ensure a stable internet connection. Clear your browser cache or try a different browser if the site doesn't load properly. If problems persist, contact TurboTax customer support for assistance. Always make sure your system meets the software requirements before installation for a smooth experience.