Problem with Atari core

[r2d2]

I am using retroarch 1.9.0 flatpak version on MX Linux. I have downloaded Atari 5200 core and when i load the core and try to load a rom i get this:

The rom i am trying to load is working fine on Altirra on Windows, so the issue is definitely not with the rom.
Can someone help me solve this issue?

[r2d2]

I followed this guide to load the bios files for atari, but after that when i try to load the atari rom i get this message that says ‘The atari computer has crashed’:

Any idea why this is happening?