To use the addons the import would be react-data-grid/addons, that would just point to react-data-grid.ui-plugins.js on the dist folder for the package;
To get the styling you would either need to copy grid's css or reference the css file on the dist folder
2.0.0
Exports two main packages (react-data-grid and react-data-grid-addons);
Both packages have independent releases;
You get all the default css styling for free, if you want a custom styled grid you will only need to override the intended classnames.
Imports for react-data-grid/addons you will need to replaced by react-data-grid-addons
If you have a copy of the default grid styling you can drop it off, if you have some custom classnames you just need to override those specific classnames