TL;DR: F-Droid isn’t referring to that, but yes, the app requires an API key for a paid service to perform unlimited requests.
Long answer:
When using the expression “non-free”, F-Droid refers to something not being free software, where the term “free” doesn’t refer to its price (free as in beer), but to it giving its users freedom to do what they want to with it (free as in speech).
However, this application in particular relies on a service called AudD, which is a paid service based on the number of API requests done. So while the F-Droid “anti-feature” list doesn’t refer to its price, this app still relies on a paid service and requires an API key upon launch (although it seems you can do a limited number of requests without one).
The Cromite GitHub page also says it supports arm32-v7a right at the beginning (for some reason later in the README it lists the platforms again without it, someone probably forgot to change it), I believe it’s the file in the releases called arm_ChromePublic.apk (not arm64), so try that
(Note: it does say it’s Android 7 or higher though, so it still might not work unless you try some custom ROMs)