What you did does not work because it should not work in OpenMandriva.
OpenMandriva has it’s own repositories and packages. To learn more perhaps look at some of the How To’s here.
Just because OpenMandriva has chosen to use dnf does not mean OpenMandriva is “just like Fedora”.
Post-edit: Forgot to mention that I don’t believe brave is in OM repositories. The advice from @Izaic should be good though.