This is a lovely song.
She is playing in an open tuning in the key of C, I believe.
On her website, she offers some music and some is free.
In standard tuning play a G with capo v adding in the fifth string pattern on open, second and third frets. Then change to D on warning.
Em for "float" and back to G on "ocean", playing an occasional csharp with it on the fourth string. I don't think it goes to a D in the chorus at any time, but the tuning suggests it.
This could be open G.
Perhaps, someone can add to this effort.