I was downloading 3.77 GB out 6.08 GB when my internet connection was cutoff and when I tried again, it keeps on failing to download. An error has occurred. Please advise.

Hello bryanocampo,

Thanks for visiting Apple Support Communities.

It appears that OS X El Capitan failed to download and an error occurs when you try to restart the download. There are some steps I can offer which may help the situation.

First, if you haven't already, restart your Mac and try the download again.

Next, look in the Applications folder (Choose Go > Applications in the Finder menu). If there's an OS X El Capitan application there, drag it to the Trash.

If the download still doesn't start, try signing out and back in to the App Store (open App Store and choose Store > Sign Out).

If the issue continues, create a new user account on your Mac and try the download there.

To create the new user:

1. From the Apple menu, choose System Preferences.
2. Click the Users & Groups icon in the System Preferences window.
3. Click the lock icon, then enter an administrator name and password.
4. Click the Add button (+) below the list of users.
5. Choose a type of user from the New Account pop-up menu.
6. Give the user a full name, account name, and password.
7. Click OK.
8. Close the System Preferences window.

Log out of your current user account by choosing Log Out from the Apple menu, then log in to the new account you created. If you're prompted to sign in with your iCloud account or Apple ID when you log in, skip this step.

From How to test an issue in another user account on your Mac

Best Regards.