Problem with module installation on staging subfolder (Magento 2)

Question

I have created a staging magento copy of live site on a sub folder, everything goes fine until now.

When I want to install module, and run magento module:status doesn't appear on the list.

The folder of module is on app/code, but nothing happens.

Any clue about this problem?

Thanks!!!

[More Info]

I'm trying to install this module https://store.plumrocket.com/twitter-facebook-login-magento2-extension.html

module.xml

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Module/etc/module.xsd">
<module name="Plumrocket_SocialLoginFree" setup_version="2.2.0">
    <sequence>
        <module name="Magento_Customer" />
        <module name="Plumrocket_Base" />
    </sequence>
</module>

registration.php

\Magento\Framework\Component\ComponentRegistrar::register( \Magento\Framework\Component\ComponentRegistrar::MODULE, 'Plumrocket_SocialLoginFree', __DIR__ );

Answer 1

Please check in your module there registration.php exist with below code with no typo:

     <?php
   \Magento\Framework\Component\ComponentRegistrar::register(
   \Magento\Framework\Component\ComponentRegistrar::MODULE,
   'Namespace_Modulename',
    __DIR__
    );

and also module.xml etc/module.xml

  <?xml version="1.0"?>
 <config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
xsi:noNamespaceSchemaLocation="urn:magento:framework:Module/etc/module.xsd">
<module name="Namespace_Modulename" setup_version="1.9.1">
    <sequence/>
</module>