I've been in a lot of meetings where people started collaborating on some project for the first time and we either don't know each other at all or we know of each other through reputation/work only. They all start in much the same way: everyone introduces themselves and gives a bit of background on themselves that's relevant to the project. If one person knows of another, they generally say so. If it's a group meeting and two people have worked together before, they'll usually say that as well.
This accomplishes a couple of things: it breaks the ice and let's everyone know generally what to expect from everyone else knowledge and skill-wise. Here are some examples of things I've said or heard in such meetings:
I'll be the SQL developer for this project. I just joined this particular company, but I've been developing database applications for this client for several years.
How great to finally meet the famous [name] I've heard so much about! Whenever [system] comes up, your name comes up along with it.
I don't believe we've met! What's your role on this project/your subject of expertise/your experience with [topic related to project]?
The goal is to make a bit of a connection between everyone and give some background to know how best to collaborate with one another. In your particular case, you can open with how much you admire the person you're working with and a bit about the work of theirs you're familiar with. People love to be known and appreciated for their work, so it's difficult to go wrong with that. If they're not aware of your background, then give them some info about that as well. If you didn't get a chance to do so in your first meeting, feel free to express your excitement at working with them at the start of your next one.
If it were a group and not just the two of you, saying, "Everyone's here, so let's get started" after greetings would be normal and common, so you aren't being as weird as you think! It's also pretty common to do a greeting and then pull up whatever you're collaborating on and just dive in. It was probably the silence more than anything that made it feel awkward. Chances are you remember it much better than they do, so don't beat yourself up about it.
If you get stuck like that in the future and are too nervous to come up with something sensible to say, it's perfectly fine to simply say that you're nervous. Again, it's giving context about you which helps them know how best to work with you. I've dispelled plenty of awkward moments by openly acknowledging them, and I've seen it work well for other people as well. Being nervous in a new situation is a normal thing, nobody is going to think poorly of you for it. Often things get awkward like that because everyone feels a bit uncomfortable, so saying so out loud can cut the tension and allow everyone to relax.