On the AR1 the nodes are installed on this path;
/home/dev/.node-red/node_modules/node-red-contrib-sparkplug/sparkplug
But that is not where the protobuf file is stored.
You will have use another method to copy that file over and depending on what method you use will determine the path.
The path you list in your forum post sounds more like an EPIC (the ‘unsecured’ is a big hint since that path only exists on EPIC PR1 and not the AR1)??
And to answer your first question, from the factory the AR1 does not support SSH or Shell access unlike the EPIC PR1.
You will need to use the ‘exec’ node in Node-RED to do file system commands.