Do doordasher’s accept cash tips?

So a weird thing happened. I live in a condo and I ordered something on DoorDash and wrote in the instructions that I would give a cash tip (since I had some left over cash I want to get rid of). I got a knock on the door and I went to get it but the door dasher had left. I couldn’t see him so I called out to him.

I said hello, and then he said hi from the elevator. I told him I had a tip for him and then he said thank you and then just went down the elevator. I was super confused by this. Was he mad I didn’t tip from the app? Or did he not read the notes?