To use an old term, "you have the cart before the horse".
What it is saying is that it it is not approved for aircraft without GPS sensor update of the FMGC.
DME/DME/IRU is the default update for aircraft without GPS (GNSS). There was originally an approval in certain countries that allowed DME/DME/IRU RNAV approaches as long as an EPE/ANP of better than 0.3 was available.