Hi.
So Plotly is in Python and it sounds like you use it to output an HTML page for you.
I guess this could be done locally and then you add the HTML to your site which makes building your site on the remote a lot locally. If you have dynamic data this becomes more complex.
Secondly, make sure that your HTML snippet that is generated by Plotly actually exists in the right place
_includes/
my_figure.html
index.md