fig2plotly() error, you must be signed in

I’m trying to use Plotly under Octave and I’ve been following the tutorial on https://plot.ly/matlab/getting-started/ .
But, when I use the fig2plotly() function, I get the following message:
"error:
Oops! You must be signed in to initialize a plotlyfig object."
I’m signed in to plotly on google chrome. I’m also running Ubuntu 16.04