Serema questions?

I have outdoor free range chickens. We lost a couple due to being roosters and a few to a racoon I think. Well...we went to a farm where a man was getting rid of his chickens to pick up a couple more hens.

They were not deplorable conditions....but they werent the best either. They chickens were healthy and well taken care of, I just personally, they didnt have enough outdoor room. We took 3 hens from him, and they are already loving the free ranging life.

WELL.....he had this tiny sweet Serema hen. He didnt even KNOW what she was...she was part of a lot of hens he got at a swap or something (he did fairs and livestock swaps). He had her all alone in a little cage outside. We felt so sorry for her. We didnt take her at the time b/c we didnt know what to do with her. Then on the way home, we just kept feeling worse and worse that we left her there. So I sent the man an email letting him know we wanted her too, and asking when we could come get her.

SO hopefully we will be adding a Serema hen to our group soon. I am assuming outdoor free ranging wouldnt be the best set up for her. And since she is the only one, should I keep her inside (and we are completely fine with her being inside)? If I do, what kind of set up do I need? Can I use an old birdcage? How do I set this up..... Help me so I can help this bird!

Thanks!