In the examples folder included in the package of the license you can find examples of how to use importListStyle, importStyles and parseStyles methods. You can find them in the examples/LayoutAndGeneral folder.
To import a list style you need to use the importListStyle method (https://www.phpdocx.com/api-documentation/layout-and-general/import-list-style-from-a-Word-document-with-PHP). For example:
$docx->importListStyle('template.docx', '1', 'myliststyle'); $itemList = array( 'Line 1', 'Line 2', 'Line 3', 'Line 4', 'Line 5' ); $docx->addList($itemList, 'myliststyle');
If the style is not applied using your custom template, please check that you are setting the correct list ID.