You talk to them about yourself, your transition, and your life. It's not a big deal. There are no real boxes to check. They may have questions along the way — just answer them, be honest, and you shouldn't have a problem. One doctor was genuinely interested and engaged in my story and was very fun to talk to; the other felt more pro forma.
The evaluations themselves are pretty straightforward — maybe 30 to 45 minutes each, conversational rather than clinical. They're not trying to trip you up or catch you in something. They're confirming that you understand the procedure, that you've been living in your gender, and that you're in a good place mentally to go through with it. Two years on HRT and living as yourself is exactly the kind of thing they want to see.
Think of it less like a test you can pass or fail and more like a conversation where they're making sure you're ready and informed. If you've been living your life authentically, you've already done the hard part — this is just them documenting it.
Try not to stress over it. I know that's easier said than done, but really, just be yourself and tell your story. That's all they're looking for.