Invalid offline activation response file - Cyptlex offline activation response

Hi i’m activating licence through Offline.
I have a CryptLex_OfflineActResp.dat file. Through UI I have a upload button to upload the dat file to a specified location.
I use npm busboy to upload a file.
After uploading the file to specified location and when I activate I get the “Invalid offline activation response file.” response from cyptlex.
Should I have to add any headers to create a file stream to upload CryptLex_OfflineActResp.dat file.

Hi, when you paste the offline activation request data in the dashboard UI, CryptLex_OfflineActResp.dat is generated which you download. Now, this file is input for

ActivateProductOffline(CSTRTYPE filePath)

function. Why would you upload this file to any location?