Maybe your download is somewhere else? You can determine the download directory from the Downloads menu on Chrome (go to downloads, select open directory).
If you go to terminal and do
~/Downloads
what message do you get? Any errors. If not, what do you see if you do
ls timimi-2-1-1-Mac
An error, or a listing?
If it was me, I'd add an .sh extension. Then (from terminal, downloads directory) chmod
chmod 744 timimi-2-1-1-Mac.sh
then attempt to run again
./timimi-2-1-1-Mac.sh
I'm going based on linux experience. I don't have a Mac. But they're obviously similar at the command line.
HTH