1. WooCommerce doesn't come with any way to create sizing tables.
  2. We bundle an example Pages → Size guide page in the demo content. You don't need any plugins to have this page. Each table on that page has table-size-chart CSS class which adds mouse over highlight.
  3. This plugin adds the "Size guide" link to product pages which produces a popup window with sizing tables. To configure it follow the steps:
    1. Go to WooCommerce → BLK Size Guide.
    2. Set the attribute to "Size".
    3. Set the page ID to the ID of the "Size guide" page.
If you have completed the actions described in this article and it did not solve your issue, you may:
Search the community forum or file a support ticket