I have tried this today, Sorry to say but
insegreto/flarum-ads is broken ... it didn't work well for between the posts (VERY BAD) .... Its may be because
insegreto/flarum-ads is using an old version of
malago/flarum-ads had the same problem but after last update between the post ads was solved and works very well).
and also there is an option in (both extensions)
insegreto/flarum-ads named "Under navigational header ad only shows on the front page" this is also not working (It always shows header ad on the front page not on other pages).
For reference look at this picture -
Last problem -
insegreto/flarum-ads shows the ads in the header on the front page .... now let's assume it has shown an ad on the front page but when the user opens a discussion and comes back to the front page, all the ads on the front page are not visible (OR disabled) ....