You can try this get the plugin directory:
$pluginPath = dirname(_____FILE_____); //plugin path
$pluginUrl = WP_PLUGIN_URL . '/pluginname/'; //plugin URL
good question
you just create one template in your plugin directory. there u use the above code.
you create one page and assign this template like this
add_filter( “template_include”, “yourpage” ) ;
function yourpage($single_template) {
global $post, $pagenow;
if ($pagenow == 'download-template.php') {
$single_template = dirname( __FILE__ ) . '/templates/download-template.php';
}
return $single_template;
}