Calculating time it takes to download content
Most likely what you have is a line with a 400kbps bandwidth. That means a maximum throughput of 400kbps.   

If you divide by 8 bits you get KiloBytes/s = 50Kbs.

1GB = 100000KB, thus 6GB = 600000KB,

600000KB / 50KB/s = 12000 seconds = 200 minutes = 3 hours 20 minutes

That means it would take at least 3 hours 20 minutes to download.   It could take significantly longer depending on network traffic.