Cannot configure the Antispam module
The module asks for an API key, as the description for the "Akismet API key" field on admin/config/antispam says:


  Please, enter here your Akismet API key. If you don't have one already, you can get it by simply signing up for a free account at Akismet.com. Note that this information is required in order to use the Akismet Service. Please, consult the Akismet FAQ for further information.


Drush doesn't report any error because there isn't any error to report. Only after you enable the module you can see its settings page, where you need to enter the API key. Even if you installed the module using the browser, you should not have seen any message about entering the API key.

If you cannot access the setting page to set the API key, you can:


Obtain the API key using the link I reported before
Use Drush to set the Drupal variable antispam_wpapikey

drush vset antispam_wpapikey $key



(Replace $key with the API key.)