I understand what you are trying to say but are you aware that you are posting to a thread in the Fusion for Apple Silicon Tech Preview area? Don't forget that we are running a non-final, non-stable, not-suited-for-production version of VMware Fusion on hardware that was announced quite some time after Ubuntu 20.04 LTS was released. That greatly impacts how easy or difficult things are going to be.
Try downloading the arm64 version of Ubuntu 20.04 from the Ubuntu website, especially the desktop version. The best and quickest option is to use the links in the Tech Preview Testing Guide and modify them a bit (because they are a bit outdated). Then you can download iso images for both the server and desktop versions. Looks an awful lot like how you have to go about getting the arm64 version of Windows but without the need of having to create a Microsoft account and joining some sort program.
Perhaps we should draw the conclusion that Ubuntu may not be the best option if one needs a Linux distro to run in the Tech Preview, especially if we look at other offerings such as openSUSE or Fedora. At least they provide the arm64 iso images upfront. Also no need to create an account and join some program.
If we take a look at NetBSD however things get more interesting but not in a positive way. Try downloading the arm64 version there. You'd first have to figure out which kind of arm64 Apple Silicon actually is and then hope you've downloaded the correct one. Clearly a result of the fragmentation that is the ARM architecture. Something SystemReady tries to alleviate (and iirc this is also what Fusion will be supporting or is already supporting).
In the aforementioned Tech Preview Testing Guide you will find something that says that you'd need at least kernel version 5.14 for things to work optimal. From experience I can tell you that that is true: openSUSE Leap 15.3 uses a 5.3 kernel but installed and runs perfectly fine. You just have to miss out on a basically just the ability of setting the resolution to anything other than 1024x768. And you'll also find that there is quite a long way to go when it comes to graphics; Fusion simply doesn't support a lot of it just yet. Hence the reason why we have to go through several hoops to get things to work nicely with some Linux distros. Windows is no exception here as Microsoft and therefore also VMware do not support running it in Fusion. The instructions on how to get it to run proves that point.
The reason why we have to jump through several hoops is us being early adopters and testing out new shiny things that are nowhere near ready to be released. If we were running on x86_64 with a final release version of VMware Fusion then the experience would have been vastly different and we would have run into the primary reasons why Linux desktops are still far away: applications and the GUI (it is either ugly, outdated or even more confusing than Windows or a combination of those). Not that using Linux as a desktop is completely useless.
TL;DR: don't mess with alpha/beta stuff, it'll bite you 😁
Anyway, to the OP: there is an issue with KDE where it does not allow you to change the resolution. I haven't seen it with xfce or gnome so using those could be a workaround. Another one if you really want to use KDE can be found in this thread: https://communities.vmware.com/t5/Fusion-for-Apple-Silicon-Tech/Changing-screen-resolution-in-VM-doe...
