WP Spreadsheet seems to operate only in read-only mode

Just installed plugin, inserted shortcode
“You can insert any text before
or after spreadsheet instance”

and empty spreadsheet appears with only PDF and Excel icons in toolbar. How does one input data?

You need to be logged in, and your user must be in one of next groups

Super user (Super administrator before 1.6 version);

I have the same problem with joomla 2.5, I have logged in as the super user and it is still in read only mode

Any ideas?