The error messages "File xxx missing", "Missing Executable Error" or "Error code -59" may appear during installation of a Steam version of the software.
To solve the problem, please follow the steps below: 

1. To begin with, uninstall the software using the standard Steam procedure.
2. Next, you need uninstall the software via the Windows Control Panel.

Uninstall the software via control panel:

• Press the key "Win + I" to access the control panel.
• Select "Apps and features".
• Select the application and click on "Uninstall".
• Restart your computer.
• Return to your Steam Library, select your application, and click "Install".
• After Steam tells you the program is finished downloading, click the "Launch" button.
• After installation restart your PC.

If the problem persists, follow these steps:

• Go to C:\Programs (x86)\Steam\Steamapps\common\software name and execute the appropriate exe file.
  
• Go to C:\Program Files\VEGAS\Software Name\ and highlight each individual file and folder.
• Now click the right mouse button and select "copy".
• Go to C:\Program Files (x86)\Steam\teamapps\common\Software Name\Software Name\ to paste the copied files.
• Then start your application.