Ionic screen orientation lock

I need to lock only my app login page to the portrait mode, I am using the below plugin but I am not able to access the sceen object of the plugin.

I tired below things to solve the issue:

-Tried removing and re-installing the plugin.
-Accessing plugin through the config.xml
-Tried referencing the plugin file in index.html

Still the issue persits, Is there any workaround to access the plugin object.