Follow the steps under “Setting up the Culture Amp <> Comprehensive Integration” in this article. The instructions look long, but they’re very quick - see below for summary:
(1) Connect in Culture Amp
Find Comprehensive under your Settings > Data Integrations page
Click Set Up Comprehensive Integration to begin
Generate new credentials for Comprehensive
(2) Link in Comprehensive
Go to the integrations page in Comprehensive
Select “Add Integration” under Performance Management Integrations
Select Culture Amp
Enter the client ID and secret key from step 2