You should be concerned about the voltage of the electrical grid of your country.
Since the link you gave is an Indian site, India's electrical grid is at 230V
Japan runs at around 100V
USA runs at 115V
That means that PSU can be used anywhere in the world
I only see one set of input voltages listed on there, but yes, it could work at 90V. The APFC circuit in it provides universal input voltage capability, basically it senses what is coming in and correctly boosts it to the level that it wants. The trade off to this is that the low the voltage you run it at the more current it needs to get the same amount of power, so it will be less efficient.
The reason it is rated for 90-264 is because electrical lines are rated as their nominal value +/-20% so it has to work with the low range of a 100/110/115/120V line and it has to work with the high end of a 220/230/240V line.