Here is the doc that explain how to build this string- https://learn.microsoft.com/en-us/rest/api/storageservices/authorize-with-shared-key#blob-queue-and-file-services-shared-key-authorization
This issue happens when the authorization signature is incorrect. Please refer to this doc for details regarding troubleshooting this error/issue- https://techcommunity.microsoft.com/t5/azure-paas-blog/the-mac-signature-found-in-the-http-request-xxxx-is-not-the-same/ba-p/3293726
Hope this helps. Please let me know if you require any further assistance and I will be glad to assist further. Thank you!