You're right. I chose the wrong drive. For anyone who may encounter the same confusion, I selected autodetect initially and the device was found. However, you should really make sure to select the appropriate drive during configuration: "Select your drive in the file system". I changed it from C to F (corresponding USB port where the device is plugged in is my guess). Then I ran the install using the utility. Thanks.
Still curious why the manual installs didn't work out...
Time to look over this manual to learn how to use RockBox