However.... looking at the wget options, omitting '-qN' won't matter for a first-time download. The option 'q' just turns off the command-line output. And 'N' is to do with file timestamps, which only matters if you are replacing older files with updated ones.
As you have managed to download the install script anyway, I think you can just go ahead and execute the other two commands:
chmod +x install.sh;
./install.sh
