The version number should be easy to find. - The current version is 1.0.0 and your version will be in the Adobe Extension Manager -but as its 1.0.0 I would guess that its difficult to have an old version....
It took me a few minutes to find the right bit for the form options the first time I used it.
In the CSS Form Builder: Edit Form Contents Section, click the Group and then the edit icon, then click on a form element and click the Type button, you should see about 14 different options, one of which is datepicker.
If its not there I would guess uninstalling the extension then go back to your Download Section in your WA account, download and install it again.