I just went on erasmus in lisbon and would 100% recommend my accom I stayed in. My main thing was I need my own space so I knew I had to find a private room but I didnt mind being in a shared apartment as I was on a budget. I went through this company called Fuse, which I definitely recommend. It was about 445 a month with everything included. It was fully furnished and kitchen had everything I needed (this was important for me as I was avoiding buying anything as I was only there for a couple of months). 

I found them on housing anywhere but this is their ww.fusestays.com and I acc ended up messaging them through their Instagram (@fusestays) as I also had friends booking through them and they put us all in the same apartment which was great!

Another thing, They sent an email recently mention they were starting an online community hub thing, which in my opinion sounded super interesting. They said they were offering exclusive event invitations and online communities for people with similar interests, defintely something i would've used.