Failure to upload asset with document cloud api

Thank you for answer @Raymond Camden , I am not sure which variables you are referring to.
See request copied from the "Getting Started" page

curl --location -g --request PUT 'https://dcplatformstorageservice-prod-us-east-1.s3-accelerate.amazonaws.com/b37fd583-1ab6-4f49-99ef-d716180b5de4?X-Amz-Security-Token={{Placeholder for X-Amz-Security-Token}}&X-Amz-Algorithm={{Placeholder for X-Amz-Algorithm}}&X-Amz-Date={{Placeholder for X-Amz-Date}}&X-Amz-SignedHeaders={{Placeholder for X-Amz-SignedHeaders}}&X-Amz-Expires={{Placeholder for X-Amz-Expires}}&X-Amz-Credential={{Placeholder for X-Amz-Credential}}&X-Amz-Signature={{Placeholder for X-Amz-Signature}}' \
--header 'Content-Type: application/pdf' \
--data-binary '@{{Placeholder for file path}}'

 to the best of my understanding, I replace the URL with the uploadUri received from the previous request (create asset). see screenshot below of the create asset:

So what I do is take this uploadUri, and send the PUT request to it along with the file I wish to upload.

This URL btw (received in step #2) is already invalid when trying to access it directly. so I don't think the problem is in step #3 but with the uploadUri received in step #2.