Hello @jalathpc_demo
I tried to create a patch:
https://github.com/LM1LC3N7/nodebb-plugin-private-forum/releases/tag/v1.3.1
I no longer have a NodeBB instance, so let me know if it works (I am honestly not sure, as /logout should be allowed as you are logged in.
It would be interesting to check if req.loggedIn is correctly set when using SSO. This could be why the plugin is not working as you need.
NPM link: https://www.npmjs.com/package/nodebb-plugin-private-forum/v/1.3.1