Foreclosure

[Saravana Bhavan]

I have won a foreclosed home in Maryland in auction. I am not sure that the former owner is still in the house.
1. Can I knock the door to find out and talk about cash for keys?
2. If he is not in the home when I go there, can I paste a letter in the door to call me to talk about cash for keys? is any of these illegal to do?
3. If the former owner had already vacated, do I still need to start the eviction process?

Thanks.