To make things simple:

1. Go to your system-settings(in Ubuntu) and choose Devices (i think, 'Apparaten' in Dutch) in the leftside panel, or just type 'keyboard' in Search;
2. Select 'Keyboard & Mouse' and look for Keyboard 'Shortcuts' panel and make new or change old shortcuts on the fly.

EDIT : IT DOESN'T WORK

Don't downvote, I keep it here until someone could take that workaround to work with some kind of keybinding. I'll delete it when that time has come

---

Take a look at xdotool and its documentation.

 $ apt show xdotool
Package: xdotool
Version: 1:3.20160805.1-4
Priority: extra
Section: universe/x11
Origin: Ubuntu
Maintainer: Ubuntu Developers <[email protected]>
Original-Maintainer: Daniel Kahn Gillmor <[email protected]>
Bugs: https://bugs.launchpad.net/ubuntu/+filebug
Installed-Size: 125 kB
Depends: libc6 (>= 2.15), libx11-6, libxdo3 (>= 1:3.20150503.1)
Homepage: https://github.com/jordansissel/xdotool/
Task: ubuntu-budgie-desktop
Download-Size: 41.5 kB
APT-Sources: http://fr.archive.ubuntu.com/ubuntu focal/universe amd64 Packages
Description: simulate (generate) X11 keyboard/mouse input events
 xdotool lets you programmatically (or manually) simulate keyboard
 input and mouse activity, move and resize windows, etc. It does this
 using X11's XTEST extension and other Xlib functions.

sudo apt install xdotool

You can then bind xdotool commands with these commands in Setting > Keyboard shortcut.

In your case, the xdotool patterns would be :

xdotool key Left
xdotool key Right

For up and down, it's... Up and Down