Dropbox can interfere with plugin installation / plugin prevents dropbox sync. Just quit Dropbox while enabling.

[Kuiriel]

This is probably less an issue with the plugin and more an issue with dropbox, so this is a courtesy tip for anyone else facing the issue.

I kept getting a failed to install plugin error on attempting to enable the Folder Note plugin. I noticed that Dropbox seemed to be stuck on syncing this plugin as it had just been installed. I tried rebooting Obsidian and reinstalling the plugin.

Temporarily quitting Dropbox allowed the plugin to install itself correctly.

Additionally, the Obsidian plugin folder 'Folder Note Plugin' is unable to sync any changes to Dropbox so long as Obsidian is open. I'm not sure which program is overruling the other.

Restarting Obsidian allows any changes to these files to be synced.

It's not like you need to twiddle with the plugin constantly, so this is only an occasional issue, but just in case.