The name of the library has been changed to lowercase letters and the library is installed using Composer

Loading the Magnific-Popup library using composer

1 Installing the patch

2 Installing the Composer Merge Plugin

$ composer require wikimedia/composer-merge-plugin

3 Adding it to the "extra" composer.json (which is in the root of the site):

"merge-plugin": {
    "include": [
        ...
        "modules/contrib/fiu/composer.libraries.json"
        ...
    ]
}

modules/contrib/fiu/composer.libraries.json - the path to the composer.libraries file.json in the fiu module

4 Run composer install

The name of the library has been changed to lowercase letters and the library...