I have tried downloading small files from google Colaboratory. They are easily downloaded but whenever I try to download files which have a large sizes it shows an error? What is the way to download large files?
Google colab doesn't allow you to download large files using files.download(). But you can use one of the following methods to access it:

The easiest one is to use github to commit and push your files and then clone it to your local machine.
You can mount google-drive to your colab instance and write the files there.
How to download large files (like weights of a model) from Colaboratory?