Ok here you have a tricky problem but it is not a difficult one.
First you need to download the Free Download Manager (FDM) available for free in in you PC or MAC.
Then the link for your backup you can download from inside this software, the good thing is you can get better speed and also you can pause in between.
I have honestly downloaded around 25GB of data per day on Average with this baby, try it out. I guess you will be able to complete the full download before the weekend.
Note: Please ensure your Modem (if you are using a Mobile Router) is having good signal coverage and connectivity.