That is not a Node-RED node package (its just an npm module).
Why did you not just install the node-red-contrib-cip-st-ethernet-ip package as i instrcuted?
In theory, had you followed option 2 as I wrote it, your existing flows would all simply just work (since node-red-contrib-cip-ethernet-ip and node-red-contrib-cip-st-ethernet-ip are almost identical & most likely 100% compatible - they are built from the the same source, except the node-red-contrib-cip-st-ethernet-ip is newer and supports strings as per your requirement!)
My thought was to get the latest version with more features like UDT, array ... bug fixes.
The site also shows a lot of good examples of JS that I thought I can copy & paste into a function node.