And if it's adsorption then that means Pressure Swing Adsorption and that means concentrating the air but wait, isn't that how an oxygen concentrator works?
5-6 bar in the HP column and ~0.5bar in the LP column. However different plant designs have different pressures, but thats the general ball park figure on a standard ASU
If you want to see how a pair of Flat Earthers have misrepresented this video, see *Peter and Pete* 's video "Peter & Pete Make Copper Metal", starting at about 14:00.