Ok adding those helped. The log now shows this:
2024.09.09 08:49:19.368 *I* [auth ] New ephemeral authentication token issued for user admin [1]
2024.09.09 08:49:45.416 *I* [logger ] Debug level for tag "ncd.*" set to 7
2024.09.09 08:49:52.473 *I* [logger ] Debug level for tag "ncd" set to 7
2024.09.09 08:49:57.138 *I* [logger ] Debug level for tag "nc.*" set to 7
2024.09.09 08:50:02.590 *I* [logger ] Debug level for tag "nc" set to 7
2024.09.09 08:50:53.104 *D* [nc ] SendNotification: sending message to "" via channel "Slack"
2024.09.09 08:50:53.104 *D* [nc ] Driver for channel Slack requires recipient, but message has no recipient (message dropped)
2024.09.09 08:51:26.293 *I* [auth ] New ephemeral authentication token issued for user admin [1]
2024.09.09 08:52:19.404 *I* [auth ] New ephemeral authentication token issued for user admin [1]
2024.09.09 08:54:04.207 *D* [nc ] SendNotification: sending message to "" via channel "Slack"
2024.09.09 08:54:04.207 *D* [nc ] Driver for channel Slack requires recipient, but message has no recipient (message dropped)
2024.09.09 08:54:09.219 *D* [nc ] SendNotification: sending message to "" via channel "Slack"
2024.09.09 08:54:09.219 *D* [nc ] Driver for channel Slack requires recipient, but message has no recipient (message dropped)
2024.09.09 08:54:26.392 *I* [auth ] New ephemeral authentication token issued for user admin [1]
Added "admin" for the recipient and I am finally getting notifications in slack!!!
Thank you to all for your help!