The preferred way to install this extension is through composer.
Either run
php composer.phar require --prefer-dist insolita/yii2-adminlte-asset "~1.0.0"
or add
"insolita/yii2-adminlte-asset": "~1.0.0"
to the require section of your composer.json
file.
Just register AssetBundle in top of your layout
$this->registerAssetBundle(AdminLte3Asset::class);
See Layout Example