Edit:

Home Page - I'm fetching a list of strings from my firebase collection. I then want to make a call to firestore storage and get the downloadable image link and store it in a list that I will pass to Page 2. The code below is how i'm getting the downloadable links.

Future> test(List images) async{
  List listOfImages = List();
  for(int i = 0; i < images.length; i++){
     final ref = FirebaseStorage.instance.ref().child(images[i]);
     var url = await ref.getDownloadURL();
     listOfImages.add(url);
  }
  return listOfImages;
}

I'm then passing the list of Images in the following manner

Navigator.push(
  context,
  MaterialPageRoute(
     builder: (context) => CarDetailScreen(
        carImages: test( car['images'])
  )),
);

Page 2 - I'm receiving a Future> that I would like to convert to a List

List map(List list, Function handler) {
List result = [];
for (var i = 0; i < list.length; i++) {
  result.add(handler(i, list[i]));
}

return result;
}

new CarouselSlider(
  items: ***["This is where I need a List"]***.map((url) {
    return new Container(
        margin: new EdgeInsets.all(5.0),
        child: 
        new GestureDetector(
          onTap: () {
                        Navigator.push(
                          context,
                          MaterialPageRoute(
                              builder: (context) => ViewCarImages(
                                  carImages: _getImages(snapshot))),
                        );
                      },
          child:
        new ClipRRect(
            borderRadius: new BorderRadius.all(new Radius.circular(5.0)),
            child: 
            new Image.network(
              url,
              fit: BoxFit.cover,
              width: 1000.0,
            )
            )
            )
            );
  }).toList(),
  viewportFraction: 0.9,
  aspectRatio: 2.0,
  autoPlay: false,
)