The Yarra Ranges have so many beautiful accommodation options for you, by the room, the house or the sprawling farm - have a look here: 

https://www.airbnb.com.au/d/healesvillemusicfestival2021
https://www.visityarravalley.com.au/stay
https://www.racv.com.au/travel-leisure/racv-club/healesville/stay.html 
(RACV resort accommodation is directly opposite the festival site)