If a song is listed as Interactive, clicking the "View" link will load the Interactive file, and will allow you to view, transpose, and adjust the zoom level of your sheet music prior to printing.
Once you're ready to print, click/tap on the Print button immediately above the sheet music, and your sheet music will display "Print Score To PDF." This file will then appear as a PDF download, allowing you to print your interactive sheet music purchase.
Do not click/tap Print at the top of your browser window, or Print in the File menu, or type Ctrl+P or Command-P - these will print the web page, not the score.
If a song is listed as Publisher Original PDF, the "Download" link will bring up the publisher's original score, and will allow you to view the score prior to printing. When clicking/tapping on this link, you will be able to Open this file (using a PDF Reader, such as Adobe Reader), or Save File to your computer.