The error AM2R_11 not found! Please place AM2R_11.zip (case sensitive) into ~/script/folder or provide it via command line arguments and try again. happens (even with the AM2R.zip file) if the folder of patcher.sh has a space in its name.
e.g.:
sh ~/Downloads/Update AM2R/patcher.sh > Script runs ok, but it doesn't find AM2R_11.zip
sh ~/Downloads/UpdateAM2R/patcher.sh > Works