If you are looking to use the End Of Day US Options Price data feed in Excel, you'll want to look up the contract identifiers to use in your formulas. An options contract identifier Apple would look like this:
You'll notice Apple's ticker symbol at the beginning followed by a unique identifier made up of a long series of numbers and letters.
If you paste this URL into your browser, you will download a list of the most recent contract identifiers for Apple (you need a free trial or subscription for it to work):
By changing the ticker you can get the contract identifiers for different companies.
Another way to download the CSV is with the API Explorer.
On the data feed page, you'll be able to select the "Options" endpoint/setting within the API explorer. Then click on the "CSV" link up top:
Now you're ready to make the API call using for example ticker AAPL:
When you hit "Execute", you'll the results on the screen and on the bottom of the page there is a "Download" button. Click that and it which will download a CSV file to your computer: