So I suppose that you need to download file of the current day... 'cause when you run "grep" command you need to match a pattern and as you may not know filename by advance, we'll do work on the date
So to have the date in the same format as "ls -l" command, the command is "date +%b\ %d" (the \ is required to protect space character)... So the command to list the files created the current day is:
ls -lt | grep "$(date +%b\ %d)"
then you can run "cut" command to only keep filename and redirect the result into your file