Receive error during installation, need some help...
With the information you've given no-one can help as you've not provided any information. You'ld be best posting this under the thread for the MODx version you are installing rather than General Discussion; every verstion of MODx has it's own support thread.
Include details such as your host, MySQL version, PHP version, etc along with details of when the Server Error occurs as Error 500 could be caused many a range of problems. Sorry can't be of more help but once you provide more details in the correct thread I'm sure someone can help.