As per Slacks instructions from the below URL generate a token

https://slack.com/intl/en-au/help/articles/360041725993-Share-a-default-sign-in-file-with-members

1. From your desktop, click your workspace name in the top left.

2. Select Settings & administration from the menu, then click Workspace settings.
3. Click the Authentication tab.
4. Next to Automatically open this workspace for members, click Download.
5. Locate the Signin.slacktoken file in the downloads folder on your computer.

After you have this you can open it in something like BBEdit and it will look like this, with T02SYFD45 being the token number needed for the script

{"default_signin_team":"T02SYFD45"}