The fight is really tough to get though without cheese mechanics at lv 3. The first round is tough to go without losing 3 guys. Even though they are advertised as lv 4-5 they have many bonus actions which would suggest they are in fact higher lv. It is doable with conversation alone but you miss out on "story stuff" if you go convo route.

I managed at level 3 ranger beast master after a few tries with the same setup as OP but it was 5-6 tries and used every defensive spell I could just to live though round one. After that many of their 3 action combos were reduced to 2 making it much more tit for tat combat. Didn't hide any of my guys or do anything you wouldn't normally do in that situation as a "first encounter". I was lucky as well as I managed to cause fear on a first hit removing one from the fight right off. Not going to lie, felt pretty good once they bit the dust and could very well have taken more tries at lv 3.