Host is not allowing me to check in late!

Jonathan2021.

Hi, i booked an activity few days ago, It was an online activity .Checkin hrs on the host's page on are 12-14.00. I was asked when I wanted to check in and said 12.30. Now host is saying he wants me to check in earlier, at 12.00, which for me isn't possible since I am travelling and can't control my arrival time. The page on the host's listing clearly states check-in hours are 12-14 which I also double checked before booking, knowing I am arriving late. What can i do now?