Plugin_Not_Installed for AES256 plugin

Have installed the AES256 native plugin into my Ionic v4 project according to this documentation:

When I try to use any of the methods, such as aes256.Encrypt, I get the error plugin_not_installed.

Here are the currently installed plugins as shown in the config.xml

plugin name=“cordova-plugin-whitelist” spec=“1.3.3”
plugin name=“cordova-plugin-statusbar” spec=“2.4.2”
plugin name=“cordova-plugin-device” spec=“2.0.2”
plugin name=“cordova-plugin-splashscreen” spec=“5.0.2”
plugin name=“cordova-plugin-ionic-webview” spec="^3.0.0"
plugin name=“cordova-plugin-ionic-keyboard” spec="^2.0.5"
plugin name=“cordova-plugin-aes256-encryption” spec=“1.1.0”