To show UPS rates with Boxify, you need to have a UPS account. So if you do not yet have one, go to UPS.com and establish an account.
You will then need to connect Boxify with your UPS account, which you can do by going to the Boxify dashboard and clicking on the button marked, "Configure UPS." Then click on the button marked, "Authenticate at UPS.com."
The first step is to enter information about your UPS account and the kind of UPS rates you want Boxify to provide to your shop: UPS Retail rates, UPS Daily rates, or your account-specific (negotiated) rates. Then click on the green "Save and authenticate at UPS.com" button.
Then use the provided link, which will open a special page at UPS.com in a new browser tab. Check the checkbox there allowing Boxify to read information for you from UPS, and log in using your normal UPS username and password.
After doing so, you will be shown a six-character code. Copy that and enter it in Boxify, in the browser tab you were using earlier. That's all you need to do authenticate Boxify with UPS. But if you later change your login password at UPS.com, be sure to authenticate Boxify again by repeating these to steps.
Should you have trouble authenticating Boxify at UPS.com, check this Knowledgebase article, which describes some possible reasons a user may encounter difficulty.