The tabs inside of this window are not accessible for VoiceOver.
The ARIA roles and attributes need to be adapted. role=tablist, role=tab & role=tabpanel are very well supported across browsers/screenreaders.
Best practices also feature a simple demo. For basic support we should add/amend the necessary roles and if we wanna go further in future, we could also think about changing the tabs into anchors and connect with the tabpanels as internal links.