At first it was a huge problem to me, use Composer someone said. What's that? Where do I start. But once I used it I realise it was easy peasy.
Before you start do the following.
Please ensure following things are enabled and installed on your machine.
Next Install Composer. For windows users it's very easy just download installer file from composer site.
Here is the .exe installer link to download Composer-Setup.exe
METHOD 1: Once You installed composer successfully. Go to 'Start' then type in 'cmd' then by using change directory (cd ../) navigate to the location on your PC (normally in C:/xampp/htdocs/ ) where you want to install the CakePHP3. Then run following command in terminal window.
(METHOD 2: also works install git bash, once installed you can right click in the folder where you want to run composer, so you don't need to cd into that folder using comand line)
composer create-project --prefer-dist cakephp/app cquiz
Voila, now give Cakephp write access to the temp folder by typing in 'Y'