I bought an album on itunes and now I can't get access to it to download onto my ipod

I have itunes match and i bought an album on itunes. when I try to drag it onto my ipod it doesn't copy and so I tried to 'download' it onto my library by clicking on the icon of the cloud with a down-facing arrow. Now all I have are a lot of dotted circles that then turn into 'clocks' that fill, then I get the circle with an explanation point in it.

How do I get access to these songs? Why do I need to 'download' from the cloud to be able to copy it onto my ipod?