Studio One 4 you purchased was a digital delivery that was placed in your my.presonus.com account as soon as you purchased it. We do not send out a box with discs in it, we haven't done that since Studio One version 2. You should have gotten a notification from the online store, which may have gone into your spam folder.
To see your purchases made from the PreSonus webshop, purchases can be reviewed by clicking on "My Orders" in your https://my.presonus.com
Login to your https://my.presonus.com
account to see the software in your account.
If you had purchased this in a store, they would have sold you an activation license that is printed on the receipt at the time of purchase.
If you had purchased the USB version from our web store you can log a support request through your https://my.presonus.com
account or by visiting us at https://support.presonus.com
If you're not sure what to do, log a support request so someone from sales can assist you.