It means you can fit a 280mm (2x140) or a 360mm (3x120) radiator on top.
When using an AIO like you are going to do there is no problem.
Only if you wanna go custom loop you have to watch for thickness of the radiator and some small other things
So again. When it comes to you, you can fit the EVGA 280mm AIO on top or in the front in your case.
And with its always with fans.
Its only when you go for a full custom loop this does not count since the rads can be all from 15mm thick up to 80mm thick monster rads.