installing cakephp 3 manually, without composer

Use Composer.

Install Composer locally, follow the Cake installation instructions, then upload the created folders to the target webhost.

Packaged app (cakephp/app) releases that include all dependencies (framework (cakephp/cakephp), standard CakePHP plugins (cakephp/debugkit, cakephp/bake, etc), required third party libraries) can be found on GitHub.

https://github.com/cakephp/cakephp/releases

It's the download with the small package symbol, named like cake-3-x-x.zip.

However, it isn't a good idea to ditch the dependency manager, as keeping the code base and the autoloader up to date will be rather tedious, and, no offense, I have my doubts that you'll be able to handle this properly if you don't even know how to stitch the app and cake packages together.

You can install CakePhp 3 without Composer.

You need minimum requirements to install CakePhp 3 and CakePhp 3 boilerplate ( fresh copy of Cakephp 3 ).

You can download CakePhp 3 boilerplate from github.

Requirements

Server

1. HTTP Server. For example: Apache. Having mod_rewrite is preferred,but by no means required.
2. PHP 5.4.16 or greater.
3. mbstring extension
4. intl extension

Database :

1. MySQL (5.1.10 or greater)
2. PostgreSQL
3. Microsoft SQL Server (2008 or higher)
4. SQLite 3

All built-in drivers require PDO. You should make sure you have the correct PDO extensions installed.

CakePhp 3 Boilerplate:

Repository Home

https://github.com/cakephp/cakephp/releases

CakePhp 3.1.4 https://github.com/cakephp/cakephp/releases/download/3.1.4/cakephp-3-1-4.zip CakePhp 3.0.15 https://github.com/cakephp/cakephp/releases/download/3.0.15/cakephp-3-0-15.zip

Download one repository and unzip where you wanted to install it.

You may get one error like ( you may not get error if you are lucky!)

Fatal Error 
Cake\Error\FatalErrorException
Error: Class 'Cake\Mailer\Email' not found 
File D:\xampp\htdocs\practice\cakephp\cakephp-3-1-4\config\bootstrap.php 
Line: 138 

Then you have to comment two line in config/bootstrap.php

//Email::configTransport(Configure::consume('EmailTransport'));
//Email::config(Configure::consume('Email'));

And finally you got CakePhp 3 installed.

[I am also new in CakePhp 3.So Please inform me if there are any wrong in my given process.]

Thanks