Go to Admin → Integrations → GoHighLevel and click Connect with GHL. Authorize Senly in your GHL location. After success, the green "Active" status appears.
Per client, you can then fill in a GHL Contact ID in the client profile — tasks, contacts and deals will be automatically synced between Senly and GHL.
No connect button visible? Then the master credentials for GoHighLevel aren't (yet) configured. Contact support.