Yikes! Let me pass this along to our team and have them look into this for you. Thank you for posting, if I have an update I will post here or a member services representative will reach out to you directly.
Its states after you click the link that USAA is not responsible for content or privacy policies of the website/company. And then as soon as you are redirected the very first thing that pops up is asking you if you opt in to receiving phone calls and emails with travel deals. Did you opt out or opt in? You probably opted in hence why they called you. How is that USAA's fault?
No, USAA does not share member information with third party vendors (Explore) without their consent (or opting in). After a detailed research into the matter with Explore, we were able to pinpoint what happened in your case. A representative from USAA will be reaching out to speak with you no later than tomorrow to review the details. Thanks again for bringing this matter to our attention, tikal.