ClickUp's API lives at https://api.clickup.com/api/v2. Personal tokens go in Authorization with no prefix. ClickUp calls workspaces teams in the API.
Generate a personal token under Settings → Apps in ClickUp (it starts pk_). In the examples it's written {{CLICKUP_TOKEN}}.
Full reference: https://developer.clickup.com/reference
curl https://api.clickup.com/api/v2/user \
-H "Authorization: {{CLICKUP_TOKEN}}"
curl https://api.clickup.com/api/v2/team \
-H "Authorization: {{CLICKUP_TOKEN}}"
curl -X POST https://api.clickup.com/api/v2/list/{{LIST_ID}}/task \
-H "Authorization: {{CLICKUP_TOKEN}}" \
-H "Content-Type: application/json" \
-d '{"name": "Created from PostTaco"}'