Making a 3×6 grid reveals something interesting in the middle column

If you start reading at the lower right M and the middle column you can make out the word Myosoti and adding the upper right S gives Myosotis. To get valid prefix and suffix you need to reverse rows 2, 4 & 6

Read going down from the upper right U

udm87myosotis745yg

The myosotis flower is also know as forget-me-not

udm87forget745yg

Let’s start by making pairs to see if we can spot a pattern

86 74 75 50 51 03 12 42 90 96 55 50 52 79 66

Looks like we have a good prefix and suffix, let’s change those from decimal to Ascii

VJK23 0312429096 724OB

The middle part has 10 numbers, could be ISBN-10 book codes. Searching on Google gives a book called Gain

vjk23gain724ob

Making rectangle didn’t give anything that looked like a passcode. Let’s try to find the keyword first. Since we have 15 characters we know the keyword is 5 letters. You can use this site to make a regex search to find the keyword. Check the help section, the string you need to input for the search is ^[4vj87c92evvrade]{5}$

The only result that is shown is Devra.

Going back to rectanlges, make a 5×3 grid

In the bottom row you have all the letters needed to spell devra. Reorder the columns as 4, 5, 1, 2, & 3

Now reorder rows as 2, 3 & 1

evc92devra874vj