Make a 4×4 grid

If you look at the 2 middle rows you can see the keyword sirens. Rearrange the columns (3, 4, 1, 2)

nxx24sirens652uy

Both codes have the same length

Read in a zigzag pattern alternating from the upper code to the lower code

yrg27truth363nu

gpz36latin862wg

First passcode is valid. For the second one, Truth in latin is Verum

gpz36verum862wg