Can I enable CommentGuard only on ads and not on organic posts?

Yes. In your moderation settings you can apply your automations to ads, organic posts, or both. That's one set of rules, not different rules for posts vs ads.

If you apply them to ads only, organic comments still show up in your dashboard and count toward your monthly limit, but CommentGuard leaves them untouched. Same the other way around if you apply them to posts only.

If you want organic comments completely out of CommentGuard, contact us. We can disable organic processing from our side. You can't switch this off yourself. Organic comments then won't appear in your dashboard and won't count toward your monthly limit.

To only change what you see (not what we process), use the Type filter in the dashboard. See How to show comments for posts or ads only?