Can not install Biznez Lite theme

Hello,

I try to install in theme many time but can not, when i install online in add theme. I was informed as:
Internal Server Error

“The server encountered an internal error or misconfiguration and was unable to complete your request.

Please contact the server administrator at admin@main-hosting.eu to inform them of the time this error occurred, and the actions you performed just before this error.

More information about this error may be available in the server error log.”

When i download in and install by downloaded file it is still error and informed me some code error.

Please kindly give me helps

Thanks in advance