Installation issue of Sips 1.0 - Worldline Atos (1.5, 1.6 & 1.7) module

[mezief]

Hello,

I have just downloaded the version 3.5.0 of the Atos module for my version of Prestashop 1.6.1. But when I try to install it I get this error message :
[PrestaShop] Fatal error in module file :/httpdjail/var/www/vhosts/xxx/httpdocs/modules/atos/atos.php:
require_once(): Failed opening required '/httpdjail/var/www/vhosts/xxx/httpdocs/modules/atos/vendor/autoload.php' (include_path='/httpdjail/var/www/vhosts/xxx/httpdocs/tools/htmlpurifier/standalone:.:/usr/local/php-5.6/lib64/php')

I checked the content of the file "atos.php" and there is this line: "require_once __DIR__ . '/vendor/autoload.php'", but I don't have a "vendor" folder in the module folder, nor in the root of my site.

Do you know where this error can come from?
Thanks !