Since you purchased it from Staples not from Adobe, it will not be in your Adobe Order History. And since you ordered from Staples, you probably received a redemption code, not a serial number. If that is the case, you need to convert the redemption code to a serial number. See this Help article for how to do that.
Although you have told us that you have downloaded the program successfully, you haven't said whether you have actually installed it. Nor have you told us whether you have registered the program using your Adobe account. If you have in fact done all of this, then as you have been told, your serial number should appear in your Adobe account.
- Sign in to your Adobe account on the Adobe.com website
- Click on the Plans menu
- Click on My Products
- Your Registered Products should be listed with the serial number.

It is possible to install the product and use it in trial mode for 30 days without entering the serial number. If this is what you have done, then you need to find the redemption code from Staples and locate the serial number at the link suggested by Nidhi in an earlier post.
As for having a box, some online sellers still sell these with DVDs. But you cannot get a boxed DVD version from Adobe.