As I do not know this extension it is hard to say but I think it is not using WebDAV protocol and cannot access the used path.
For file access there are already some topics about this like "Save a file created in Node Red on to CtrlX CORE" or more common "How can I upload a file, e.g. a configuration for my machine and how can I access this file".
Useable pathes to the active configuration are:
/var/snap/rexroth-solutions/common/solutions/activeConfiguration/node-RED
/var/snap/ctrlx-node-red/current/solutions/activeConfiguration/node-RED
See also further useful information in our how to collection.
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