If XPM NSUs are instantiated in the RTL, then the aperture for each NSU needs to be defined in the XDC. The command below shows how to set an aperture on an NSU using an XDC constraint.
set_property APERTURES [list \{0x201_0000_0000:0x201_0000_FFFF}] $nsu_0
No two NSUs can have the same addressing apertures, otherwise the tool would throw the error as shown below.
Figure 1. Aperture Error