Installation problem with on/off shim

I’ll start by saying I know next to nothing, so please bare with me.
I have a Raspberry Pi3B+ running Octoprint to control a 3D Printer and nothing else. It all works perfectly but I want to be able to power down the Pi safely without needing my laptop next to the printer and so I bought the Pimoroni on/off shim.
My problem comes with needing to install the one line code to make it work. Since it talks about using a terminal window to load that code, I assume this requires a keyboard and monitor attached to the Pi to be able to see it? Since I don’t have that hardware attached, does this mean that I can’t use the on/off shim?

You “should” be able to do that via SSH remote session. Assuming that Pi has network and Internet access. And SSH is enabled.
How to SSH Into Your Raspberry Pi (

It bears mentioning that the On / Off Shim installer is written for Pi OS (AKA Raspbian).
It will likely fail on another operating system etc.

Thanks very much for your response. I’m having a problem with the ssh because the Pi won’t accept my passwod ( which I know is correct).