Be sure not to close the container - the oysters need to 'breathe'.

If oysters are safe to eat, they should be tightly closed or they should close tightly when you tap them. And then they should be open - and not just a crack - after you've steamed them, if you do. I wouldn't serve them raw unless you know when they were caught. And for future reference, if you're going to refrigerate them, I would put the container over (not in) ice water in the fridge. Or over damp seaweed.

This past thread on the topic has some tips for you: https://food52.com/hotline/26043-raw-oysters-how-long-can-i-keep-them