As the command is posted here, you have no spaces between the command and its various options, plus you neglected to include the option flags "--volume" and "--applicationpath".
Here is an Apple article with the necessary instructions...just make sure to note the actual spaces between options:
Create a bootable installer for macOS - Apple Support
Here is the command from the Apple article:
sudo /Applications/Install\ OS\ X\ El\ Capitan.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume --applicationpath /Applications/Install\ OS\ X\ El\ Capitan.app
Assuming your USB stick is named "64GBCruzerBlade" with no spaces in the name, then here is the command you should have used:
sudo /Applications/Install\ OS\ X\ El\ Capitan.app/Contents/Resources/createinstallmedia --volume /Volumes/64GBCruzerBlade --applicationpath /Applications/Install\ OS\ X\ El\ Capitan.app
Make sure not to use any spaces in the name of the USB stick as that just makes things much more difficult & confusing.
FYI, in the future when posting Terminal commands it is best to use the "Code Insertion" tool whose icon looks like "</>" on the forum editing toolbar. This "Code Insertion" tool makes it much easier for us to read any Terminal commands & messages since characters & spaces are more legible due to a different font used by the Code Insertion tool. The command line is very unforgiving so it is important to be able to clearly distinguish each character including spaces.