Let’s start by making pairs to se what we have

ac 97 7b 76 a8 7d 96 7c 86 87 9a 87 98 96 78 ac 76 ae 7d

Look at where numbers should be in the passcode format, they all start with a. Hex atbash using this index

0123456789abcdef
fedcba9876543210

53 68 84 89 57 82 69 83 79 78 65 78 67 69 87 53 89 51 82

Convert decimal to Ascii

5DTY9RESONANCEW5Y3R

The range of the digits is 1 to 5. Good for a polybius square

urkezvensusannaereedvenm

4kez7susannae3d7m

Using a regex search we know that Us is the only possible keyword

Make a 6×2 grid

Reorder columns as 4, 5, 6, 1, 2, 3

9krs8usz4a2q