Best way to look for long-term accommodation?

I’m going to volunteer and live in Siargao for a month in June, and I’m beginning to look for accomodation for that time. I’m hoping to find listings for accommodations that are safe and reliable. I’ve checked Airbnb, but they’re too expensive for a month stay, which I believe is already considered a long-term stay. I also joined a couple of Facebook groups, and I’ve been receiving some listings, but I don’t know if I should fully trust them 100%. Safety is obviously my main priority while living there for 3 to 4 weeks.

If any of you have stayed on the island for that long, or are locals please let me know what is the best way to approach this, because honestly, this is the first time I’ll be doing anything like this so I’m a little bit nervous.

Salamat kaayo/salamat karajaw!

Thank you in advance!