"Mattermost authorization message not appearing"
"To fix this I needed to open web developer and look at the traffic. When you run the slack command you will see an "execute" command is run in the traffic. You click on that and look at the http header response. The header response will have a message telling you to give gitlab permissions to run the command using your account. You then take the URL and paste it into a new tab and it will bring you to the right page. Then you can just click approve. "