Hi Suraj,
AAM will not auto create traits based upon the signals in uploaded file. You will have to create traits in advance before uploading offline data.
Also, ensure that traits are created well before uploading the file. Whatever you create or edit in AAM UI, it takes 3-4 hours to take effect.
To create traits in bulk from the signals in file, you can use the BAAAM tool.
Bulk Create
Thanks,
Varun Kalra