Troubleshoot Direct Variation Link in WooCommerce

I need a way to directly link to specific variations in my woocommerce shopping cart. I tried this plugin: [login to view URL] but it didn't work. :( I tried multiple different things- I activated the stock wp theme. The plugin gets some great reviews, so I imagine the problem is most likely on my end. Here's one of the products: [login to view URL] 2 variations - one for 9" and one for 13" (depth) the default is set to 9 so I tried this to bring up the 13" already selected: [login to view URL] I tried multiple renditions, but just couldn't make it work. Can you help me out? Nothing in WP core files or master template file can be changed. i need all changes made in the child theme or plugins.