Here's a shortcut that is going to save you a lot of time. First go to select the material you want to use (from floor's properties), Highlight the text in the material field and use Ctrl + C (to copy), exit out the floor properties setting. Next, go to the material parameter that you want to place (wall properties in this case) and use Ctrl + V to paste the text in the field.
You are done!
|Ctrl + V to paste material to Wall Layer|
This little trick will let you assign material without getting into the Material Browser at all. Using this method will save you lots of time during the process. You can apply the same concept on literally any kind of family with material parameter in Revit.