Creating a Big Sur bootable disk

It seemed easy when I first looked at the process, but now I am in the weeds.

I downloaded the Big Sur OS. It looks like it is in the Applications folder,

but I also have it on a separate flash drive, just in case.

Here's the folder and contents from the flash-

I've also got the target flash for my bootable disk and have formatted it appropriately-Mac OS Extended (Journaled), named MyVolume.

I opened the Terminal app and pasted the recommended command-

sudo /Applications/Install\ macOS\ Big\ Sur.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume

But I get this error message, and I am not sure what it means.

But there seems to be an Installer there! If I click on Install MacOS Big Sur in Applications, the install process begins, but I don't follow through 'cause I'm not sure if it's going to try to install on my HD. I do not want to install on this HD, I want it to create a bootable disk for a different computer.

In rereading all the instructions while writing this, i saw the note about doing the following on Sierra-append --applicationpath to your command &c. and thought maybe that extra bit was my problem, because I am running High Sierra. Kinda like Sierra, right? Not.

I got an error message saying that applicationpath is deprecated in MacOS 10.14. In other words, it did not compute..

Any assistance would be appreciated. Otherwise, it's the Apple store for me. It's a nice place with great people, but at least a 4-hour round trip!