Error: "OAuth Error: team_not_authorized" attempting to activate the slack securlet.

• The Slack Account must be Enterprise level. 

• You must email [email protected] and tell them you want to enable the Discovery APIs for your organization. Slack verifies that the email address matches that of an Org owner and enables the integration. You must perform this step in order for your Slack Organizations to be whitelisted for access to CloudSOC.

Upgraded the account to enterprise-level and verify all other prerequisites are met.

To view which Slack account the customer may have: 
1. Open Slack console. Click on Account and Profile on the left side.
2. Then click on Plans on the top Right. Click on Compare Plans
3. You must have "Slack Enterprise Grid" or "Enterprise Select" to activate Slack Securlet in CloudSOC

Reference Slack Securlet Tech Doc for requirements and prerequisites.