TLDR: Use any browser on mac or windows, use Safari on iPhones, use Google Chrome on Android.

In release v3.1, the decision was made to disable the ability to download files on mobile browsers due to inconsistent support.

"All browsers now open the requested file in a new tab. To visually reflect this change, using the mobile version of floatingfile will show different buttons indicating the functionality (download or open)."

-v3.1 Release Note

A comprehensive list is now being generated for each device and browser so you can expect, beforehand, which browsers will enable the best experience. Notice something wrong? Don't see your OS or browser? Please submit a ticket or message me. Here are the results as of v3.4:

OS	Browser	Supported?
macOS	Safari	Yes
macOS	Chrome	Yes
macOS	Brave	Yes
macOS	Firefox	Yes
macOS	Edge	Yes
Windows	Safari	Yes
Windows	Chrome	Yes
Windows	Brave	Yes
Windows	Firefox	Yes
Windows	Edge	Yes
iOS	Safari	Yes
iOS	Chrome	No
iOS	Brave	No
iOS	Firefox	No
iOS	Edge	No
Android	Chrome	Yes
Android	Brave	Yes
Android	Firefox	Yes
Android	Edge	Yes