anticapitalista
I just downloaded the deb from the site
sudo apt install /home/myusername/Downloads/megasync-Debian_11_amd64.deb
and it worked fine.
Is your antiX-21 up to date?
Did you do sudo apt update before installing the deb?
Have you added any third party repos? inxi -r will help.
Philosophers have interpreted the world in many ways; the point is to change it.
antiX with runit - leaner and meaner.