Extract the files in your server, and run it. immediately you will get the error: Internal Server Error
CDbConnection failed to open the DB connection.
Have done that, can confirm the problem and the solution!
Help us to help you!
Provide your LS version and where it is installed (own server, uni/employer, SaaS hosting, etc.).
Always provide a LSS file (not LSQ or LSG).
Note: I answer at this forum in my spare time, I'm not a LimeSurvey GmbH employee.