You need to have a Jira issue created first so then you can save it as a Template
Go to your Jira instance
Go to Apps
Find new Apps
Type "Easy Templates for Jira
See the app appeared in a search result
Click "Free trial" to install the app
Alternative way to install - do it from Atlassian Marketplace Listing
Get an application view Atlassian Marketplace
Get an application view Atlassian Marketplace