Hello,
I installed the component again, as well as the plugins.
When I tried again, a confirmation email was sent to the email address of my test user requesting deletion. Clicking on the link worked too, but then nothing happened anymore. No further emails came in, and the admin email address that is supposed to receive the emails with the requests received nothing.
This time, however, it DID appear in the "Activities", and it was possible to delete the account there.
Unfortunately, it did not delete the posts in the Kunena forum, only the name of the poster and his account is removed.
In the settings of the extension, I have under Kunena with the setting "Post/Reply Content Replacement" clearly put "Removed by user", and "Replace Post/Reply Content" set to "Yes".
In the meantime, I have tried again with another test account, but no emails at all come in anymore (unless they are extremely delayed?), even though it did work the first time. It seems that the component sometimes does and sometimes doesn't send emails out.