[Plugin: WP PHPList] Much easier just to integrate it yourself…

Just grab the head and foot information and put it in the PHPList header / footer configuration. There, done. Then you are not restricted to the one-field form that this plugin imposes — fine for simple sign-up forms, no good for extracting membership information or collecting data for member stats.

https://www.ads-software.com/extend/plugins/phplist-form-integration/