What feature must be enabled to use Multi-Channel Funnels?
- Advertising features
- In-page Analytics
- Custom dimensions
- Goals or Ecommerce
The Multi-Channel Funnels reports are generated from conversion paths, the sequences of interactions (i.e., clicks/referrals from channels) during the 90 days1 that led up to each conversion and transaction. Analytics compiles conversion path data for any Goal or Ecommerce transaction you define.
Read more here: https://support.google.com/analytics/answer/1191182