I also got offered a free trial from Clear a few weeks ago while getting into the security line, but the system wouldn’t work properly with my ID (he said it works better with passports, which I wasn’t carrying with me) so the rep just had me follow him to the front of the line, gave my ID to the TSA agent, and send me on my way. Clear doesn’t appear to need an interview, but pre-check does. You can have just clear to skip the line but not the security check.