Make a 4×4 grid

Reverse rows 1 & 3

Read going down from the upper left B

bcu26follow452oq

Make a 4×5 grid

Read going left from the upper right T

ttxsesetruthnotrquyf

Numbers are written in latin using the first two letters

ttx66truth934yf

The code returns invalid. In latin Truth is Veritas

ttx66veritas934yf

Let’s start by making pairs with the numbers

15 14 32 45 43 31 26 29 29 26 32 14 23 15 44 44 44 16 21

The – is a hint to deduct the numbers from 100

85 86 68 55 57 69 74 71 71 74 68 86 77 85 56 56 56 84 79

Convert decimal to Ascii

UVD79EJGGJDVMU888TO

Rot -1 gives

TUC68DIFFICULT777SN

For some reason the code returns invalid. After a bit of bruting the last letter should remain O

tuc68difficult777so