You can use Zapier to do this so that when a student pays for a course on woocommerce, they are automatically enrolled in your Thinkific site. You can take a look at this articles for more info:
so this requires a paid plan? you can't do it on the free plan?
Yes, Zapier is only available on our paid plans. In particular the ability to enroll students into courses using Zapier is only available on our Business plan and above.