Grateful or not?

I just had a second-round interview (woohoo!) with a company I’m really excited about. I had a great conversation with one of my potential future managers, and I feel it went really well!

Now, I have a question:

Since the meeting was organized by HR, I don’t have the manager’s email. Should I connect on LinkedIn to express my thanks, or is it better to keep quiet?

I appreciate any advice! Thank you!