Refer to the TikTok API document I referenced earlier. That is the kind of document from TikTok you should work from. If you do not have that then talk to the person you are doing this work for and ask them for it. All we know so far is that the base URL for that service is https://seller-us.tiktok.com/product/manage - but we don't know the names etc. of any parameters. Nor do we don't know how the payload should be defined. etc. etc. From the example TikTok URL I posted you can see that TikTok's requirements are _very_ different than those for Example 7. It is likely that the TikTok APIs you are trying to use are similar.Example 7 assumes that there is a website at the other end which is expecting multi-part form data and that one of the inputs is a file. It has no notion of authentication. It is also highly unlikely that the TikTok API works like that.
Example 7 is just that an EXAMPLE that works under specific conditions - and those conditions are set by Scott's website. As I said before you cannot just change the URL and expect it to work - it won't.
Your last question, about keys, we cannot address until you have got the basics right - and you have not yet done that.
1) Look at the TikTok URL I posted
2) Locate similar documentation for the API you need to call.
3) If you still can't find documents then ask whoever tasked you to do this to give you the documents or at least to give you an example in another language. Java, Python, whatever ?
4) Show us the docs or the sameple. So far all we know is that the base URL to call is probably https://seller-us.tiktok.com/product/manage
PLEASE read all of this and respond to the questions if you want more help. Right now we are going around in circles because you are either not listening or we have a language issue - or both.