알아보다 has two senses and both turn up here. Looking into or checking out: 가사 자세하게 알아봤고요 'we went through the lyrics in detail', 가볍게 알아보는 데 'somewhere you just have a casual look'. And recognising a face: 이렇게 알아봐 주시고 반가워해 주면 좋죠? 'it's nice when people recognise you and are glad to see you', 뒤늦게 알아본 사장님 'the owner who recognised him belatedly'. -게 supplies the manner.