The time it takes to download 50 GB of data depends on how fast your internet download speed is.
If you have a high speed fiber optic internet connection then downloading the 50 GB of data could be done in a few minutes.
If you have a slower DSL internet connection then it could take you 15 hours to 24 hours or even as long as a few days to download the 50 GB of data.
For example if you have a download speed of 10 MB per second then you could download the 50 GB file or data within 8 to 12 hours.
Other factors such as other data traveling through the internet connection and if other people in your house are using internet can slow down the download speed of your file.
When downloading large files such as a 50 GB file I usually download the files that are large like that overnight or when I'm away from home.