My channel has been monetized but the ad company insist I put an ads.txt file but I can’t. I used direct developer, is there anyway around this
You need to ask this in the Developers side of the forum. You are on the user side. Click the Developers link at the top of the page to go to the Developers section.
@ToonX, if you don't get an answer here ask in the Direct Publisher section:
https://community.roku.com/t5/Roku-Direct-Publisher/bd-p/roku-direct-publisher
Never mind, it looks like you already tried that.