Atbash will easily reveal the solution

ivlixxlxixxliivxxliivliivxxxlxixxlivxxlxxlxixlxxxliilvxxliiiliivxxl

Those are all roman numeral but something is off. Reverse the string and split at every L

lxxvii liii lxxv lii lxxx lxix lxx lxxvi lxxix lxxxvii lvii lxxvii lxxix lxxi lvi

Convert roman numerals to decimal

77 53 75 52 80 69 70 76 79 87 57 77 79 71 56

Convert decimal to Ascii

M5K4PEFLOW9MOG8

Reverse

8GOM9WOLFEP4K5M

The string starts with 51 which when converted from decimal to Ascii gives 2. Let’s substitute \ with + and / with – and do the math

Start at 0 then add or subtract the corresponding value of the code

Get all the results

51 86 90 84 57 83 65 77 83 65 82 65 74 50 70 51 88

Convert decimal to Ascii

3VZT9SAMSARAJ2F3X

Looking carefully at the code you can see the keyword Nzeer in the middle written in reverse.

Let’s reverse the code

fdzikdsasxnzeerarizvfhbwu

Remove the Nzeer part, this will become your passphrase

fdzikdsasxarizvfhbwu

Use Vigenere to reveal the prefix and suffix

Passphrase: nzeer

Message: fdzikdsasxarizvfhbwu

Result: sevetqtwognsevesixsd

Looks like we have it but something is off. Make a 5×4 grid

Read right from bottom left

sixsdnseveqtwogsevet

6sdn7 q2g7t

Now reinsert the Nzeer keyword

6sdn7nzeerq2g7t