If you're signed in with your Google account, this will load the contents of your Google Drive. Click Go to Google Drive and sign in to your Google account if you aren't logged in automatically. Double-click the folder you want to copy to open it. Scroll to the bottom of the contents of the folder and press Ctrl+A on Windows, or press ⌘ Command+A on Mac. This will select all the files in the folder. Make sure you have only files selected, and not folders. If you have any folders selected you'll need to deselect them. This will make a copy of each of the files you selected previously. Each copy will be named with "Copy of..." in front of the original filename. On a Mac with a trackpad or a magic mouse, you can click on a folder with two fingers, or you can hold Control and click instead of performing a right-click. This opens a pop-up menu. Click the {"smallUrl":"https:\/\/www.wikihow.com\/images\/c\/cc\/Android7arrowback.png","bigUrl":"\/images\/thumb\/c\/cc\/Android7arrowback.png\/30px-Android7arrowback.png","smallWidth":460,"smallHeight":460,"bigWidth":"30","bigHeight":"30","licensing":"<div class=\"mw-parser-output\"><p>I edited this screenshot of an Android icon.\n<\/p><p>License: <a rel=\"nofollow\" class=\"external text\" href=\"http:\/\/en.wikipedia.org\/wiki\/Fair_use\">Fair Use<\/a><br>\n<\/p><\/div>"} to out of the folder you're currently in and select the location you want to create the duplicate folder in. It's the folder icon with a "+" on it in the bottom-right of the pop-up menu. You can name the folder exactly the same as the original folder, or you can name it something different. Clicking the checkmark button creates the new folder with the name you entered. This moves the selected files to the new folder you created. Now you have a copy of a folder containing the same files.

Summary:
Go to https://drive.google.com in a web browser. Double-click the folder you want to copy. Select all the documents. Right-click on any file and select Make a Copy. Right-click on any of the selected files and click Move to. Navigate to the location you want to create a new folder. Click the New Folder icon. Type a new folder name and click ✓. Click Move Here.