If you have a fractured rib can you still get up and walk around or is it too painful?

Usually ok to walk. The pain can be quite significant and it generally hurts to cough or even to breathe. I found an interferential stimulator applied to the area of the broken rib or ribs can relieve the pain quite successfully.
You can walk. With one rib fracture, you should be able to get up and walk. It can be painful, and you might need pain medications, but mobilization is recommended.