Step 1. Install and activate
Search and install it on WordPress dashboard or download it from Plugin Directory. It requires Nginx Cache Controller plugins, so you need to install and activate it.
Step 2. Choose theme for mobiles
Goto [Theme] → [Customize]
Click [Mobile Theme]
Choose theme you want to use for moble, then save changes.
Never forget to access from mobiles or User Agent switched browser to check themes are working.
You may flush Nginx cache or CloudFront Cache.
To force Nginx Cache, check Force deleting Nginx Cache