The Digikey (DK) BOM manager is tied to the company name that is tied to your DK login; so I don’t think you can get at as he/she intended.
Also, once you do open the parts list, it looks like you have to place orders to 3 different suppliers; but you can buy the heatsink from Digikey and the other item from Newark is marked “Do Not Stuff”, so it’s not as bad as it looked initially.