When you set trigger keywords, the match mode decides how strictly a comment must match before IGMsg sends the DM.
Exact match
The comment must equal one of your keywords exactly. Best when you tell followers to comment a single word like "PRICE" and you want to avoid accidental triggers.
Contains match
The DM fires if the comment contains any of your keywords anywhere in the text. Best for natural comments like "what's the price?" - the word price still triggers it.
Any comment
Every comment on the post triggers the automation, regardless of wording. Best for giveaways or lead magnets where you want to reply to everyone.