Create a link plugin in Ckeditor 5

Question

Guys, I was creating a plugin in Ckeditor 5 and I stopped with a situation that I can not continue, I already searched the entire documentation but I find nothing, the documentation is very bad, it seems that they hide the information to be able to sell plugin.

I have this code, it should create a Section and a (link tag) inside the Section:

editor.model.schema.register('section', {
    allowAttributes: ['class']
});
editor.model.schema.register('a', {
    allowAttributes: ['class', 'href', 'target', 'download']
});

editor.model.change(writer => {

    const section = writer.createElement('section', {
        class: 'button'
    });
    const link = writer.createElement('a', {
        href: 'https://dominio.com/file.pdf',
        target: '_blank',
        download: 'file.pdf'
    });

    writer.appendText('DOWNLOAD', link);
    writer.insert(link, section);

    editor.model.insertContent(section, editor.model.document.selection);

});

Only the result I get is:

<p>DOWNLOAD</p>

I can’t create Section on my own, let alone pass attributes to tags, someone already created a plugin in Ckeditor5 to help me?