Bought Lenovo Legion 5 for my fiancé to play Age of Mythology, but we're having trouble with a popup error. Can anyone help?

Maybe this might help? Here are some discussions that might be related to your issue: Steam Community Discussion or YouTube Tutorial.

@Avery
That seems to be a similar issue. However, he’s facing the issue with the re-release, not the old version. Would this still work? His problem is that the game won’t even launch, not that it starts then crashes, you know?

Go to the browser and get the latest NVIDIA drivers for your GPU, forget his or that app, just update the graphics drivers. If it was up to me, I’d uninstall all the NVIDIA apps.