APT is the package manager/dependency solver for the Debian ecosystem, i.e. it manages .deb packages installed by the DPKG program. Fedora software is based on .rpm packages, and thus uses DNF, the package manager/dependency solver for the RPM program, instead. This document gives a brief overview of the most common APT commands one might find in tutorials and their DNF equivalents.
@florian That does not answer his question.
DNF should work for him unless he has gotten confused and tried a fedora command on a different machine.
@ineedhelp12341 could you run the command uname -a and post the result here so the rest of us are certain we are providing the proper information to assist you.