Install without composer

I’m pretty sure that is a silly error, but I cand find the problem.
This my dir structure and the autoload file

And this is the error:
Fatal error: Uncaught Error: Interface ‘CoreInterfaces\Http\HttpConfigurations’ not found in /var/www/vhosts/bierbath.com/httpdocs/squareapi/vendor/square-php-sdk-master/src/ConfigurationInterface.php:12 Stack trace: #0 /var/www/vhosts/bierbath.com/httpdocs/squareapi/vendor/autoload.php(58): require() #1 [internal function]: {closure}() #2 /var/www/vhosts/bierbath.com/httpdocs/squareapi/vendor/square-php-sdk-master/src/SquareClient.php(56): spl_autoload_call() #3 /var/www/vhosts/bierbath.com/httpdocs/squareapi/vendor/autoload.php(58): require(‘/var/www/vhosts…’) #4 [internal function]: {closure}() #5 /var/www/vhosts/bierbath.com/httpdocs/squareapi/index.php(9): spl_autoload_call() #6 {main} thrown in /var/www/vhosts/bierbath.com/httpdocs/squareapi/vendor/square-php-sdk-master/src/ConfigurationInterface.php on line 12

I tried to reupload all the files from the repository but nothing.

Thanks again for your help.