What would be less ambiguous would be when you download an installer for an app then the installer installs that app and doesn't attempt to trick you in to "accept"ing what you think is the initial app install but is in fact an entirely different app.
If you really wanted to let them add apps people don't want then at the point of download an unchecked box could have an offer for unrelated software and that offer would state something like "software we're getting paid to have installed on your computer". That too would be unambiguous.
It's like someone offers you a bag of sweets and as you take them they say "you're fine with cryptosporidium" under their breath; you think they muttered some marketing slogan and instead you get ill from the sweets. Perfectly acceptable, you even had chance to find out what was in the sweets /s.
Aside: What's your startup?