First of all, I note that the plugin was last updated in 2014 so that explains why it does not work with the mobile app. Secondly I note that the plugin is maintained by eledia who are a German Moodle partner so I suggest you get in touch with them, preferably with a proposal for funding the mobile app access. https://eledia.de/
Moodle for mobile
can not register for a course in a mobile app whene using a key enrollment plugin
thank you for your response
I would like to download the Self-enrollment zip file plugin, help ? please and I would like to know if it is possible to add some web service to plugin so that it can be used from mobile app ?