Albums typically come in both 320kbps MP3 and FLAC. Locate the album on your purchases/music page, and click on the "Download" button. From here you can select the format to download in and whether to download direct. Please note some albums do not have a FLAC version available.
The downloaded ZIP file will contain the tracks in the format you've chosen, and a copy of the album cover image. Some albums may contain extra files. These will be inside a folder named "bonus".
You can also download tracks individually by clicking on the download button beside the track name. Tracks are served as 320kbps MP3. Depending on your browser, you may either have the correct file name for the track as it appears in the album download, or a file name consisting of a bunch of numbers. Both versions are the same file, and you can rename the one with only numbers afterwards.
If you don't want to download the album or tracks, you can stream the album at 320kbps quality by clicking on the play button for the track you want to listen to.