How to get a link to entity_reference in ListBuilder?
One possibility is to use the Link render element, and by using the canonical link for the Adherent entity. This assumes that the Adherent entity type definition has a canonical link, and that the route is defined in your module's routing YAML.

$row['adherentid']['data'] = array(
 '#type' =&gt; 'link',
 '#url' =&gt; Uri::fromRoute('entity.adherent.canonical', ['association_adherent' =&gt; $id]),
 '#title' =&gt; 'My link',
);


Another possibility is to render the field, and use the display mode that provides a link to the entity using the entity label. However this is less accessible in the documentation to look up within a reasonable time.