Error durring the addition of a plugin - by: sylvain.galopin

With projeqtor V6.0.8, when I add the plugin 'translationFrench' (Plug-ins->Plug-ins management->available plugins (local)->click on the button +)

I get the following error:
17-02-06 13:49:35.583 ===== TRACE ===== New plugin found : translationFrench_V1.2.zip
17-02-06 13:49:35.583 ***** ERROR ***** Impossible to load class ZipArchive<br/> => Not found in ../model/custom/ZipArchive.php <br/> => Not found in ../mod/ZipArchive.php <br/> => Not found in ../model/persistence/ZipArchive.php <br/>
17-02-06 13:49:35.583 ***** ERROR ***** EXCEPTION *****
17-02-06 13:49:35.583 ***** ERROR ***** on file '/var/www/projeqtor/model/Plugin.php' at line (431)
17-02-06 13:49:35.583 ***** ERROR ***** cause = Class 'ZipArchive' not found
17-02-06 13:49:35.583 ***** ERROR ***** => #0 /var/www/projeqtor/model/Plugin.php (65) -> getMetadata()
17-02-06 13:49:35.583 ***** ERROR ***** => #1 /var/www/projeqtor/plugin/loadPlugin.php (53) -> load()