There are many options for that type of accommodation. Many friends rent a room in a villa (usually with swimming pool) for around 500USD per month.
Renting a whole house might be more complicated though - i.e. pay for 12 months at once as Miles wrote.
Join those Canggu related Facebook groups. Canggu community Fb group: people share a lot of info on them & often put up ads for rooms. Acroyoga Canggu Bali: a cool activity with a nice community, if you're interested in trying something new & meeting new people who could help you, then that's for you.
Btw, Ubud is a much better place to be a digital nomad.
I was in Canggu for a month or so, internet is slow, the DN community is tiny & it's full of temptations/distractions (parties & short term "excited" crowd).
In Ubud you will meet much more nomads, have better internet & less temptations (less party & more relaxed atmosphere). No surfing in Ubud though! Just my 2 cents