There is currently a defect under review for double opt-in verification emails not being delivered for Luminate. This article provides a product workaround for double opt-in in the interim.
To setup a workaround for double opt-in, you can edit your "Thank you for registering" emails to contain link to add the user to an interest. This interest can then be used further to refine and target your audience.
If you have questions on how to set this workaround up, please contact Support and reference this KB article.