Start with the article Get Field IDs - via REST API to understand how you can collect your field id.
Step 1: Add a PTC Create Issue Automation macro to your PTC Template or any Confluence page
Following the guide Create a Simple PTC Template
Step 2: Configure the PTC Create Issue Automation macro
Fill in all the required fields.
Switch to the Add fields tab
Add a field id of your choice (in our case “description”)
“description” is the field id from the Jira Field “Description”
Click the Add Field button
Add a Placeholder of your choice (in our case “__Issue Description__”) (it is also possible to set a static value for your Jira Field Value)
Save your page
Multi line format
It is possible to combine a Jira added field placeholder (e.g __issue description__) with a PTC Placeholder macro to set the type to “Multi Line”.
Additionally, combined with a PTC Default Value macro a multi line default value can be used.