Thanks Sunil.
Though, I must accept I did not fully understand what you are suggesting.
Instead, I used the urls created by erpnext itself which it sent through mail. Now I am able to get the backup files and unzip and untar them.
But now I am facing another problem.
When I run the command "frappe --restore DBNAME SQLFILE --force" I get the following error.
I must mention here that the backup file was created using erpnext version 3 and I am trying to restore it on version 4.
Another problem I am now facing is that after this error, I can no longer visit my erpnext login page by going to localhost:8080.
It says Internal Server error.
Regards
Satish Gupta