When I wanted to select an ISO none of them popup its just blank
And in some video I found they get the menu when they right-click the pc
Which I don't get why

Did you put your ISOs into your vm_computers directory? If you didn't change the location, it's supposed to be at .minecraft/vm_computers. You put the ISOs into vm_computers/isos.

I'm just going to close this since I assume that it worked.