Unity3D isn’t officially supported on Fedora, only RHEL & Centos. It will work fine, it just needs a little tweak.

You can install Unity Hub by following the instructions for RHEL/Centos here: https://docs.unity3d.com/hub/manual/InstallHub.html#install-hub-linux

After doing so, you’ll probably get a blank screen:

If you run Unity Hub from the console you’ll see the following error:

ERROR: Licensing SDK logging callback is not registered. Please use 'registerLoggingAdapter' function from the SDK to do
so.
If you try running the licensing SDK directly you'll get this error: 

/opt/unityhub/UnityLicensingClient_V1/Unity.Licensing.Client
No usable version of libssl was found
[1]    694717 IOT instruction (core dumped)  /opt/unityhub/UnityLicensingClient_V1/Unity.Licensing.Client

You can see from the error that Unity is looking for an older version of SSL that is present on RHEL/Centos systems, but not newer version of Fedora.

To fix this, just install a compatibility version of SSL and kill any running versions of Unity Hub

sudo dnf -y install openssl1.1 && killall -9 unityhub-bin

Once that’s done, Unity Hub should work as expected!
If you’re still having trouble, a full reboot should do the trick.