Unzip and place the _random folder inside YourDatapack/data
This way you will be able to use all the functions and predicates inside _random.

Here how to use the datapack features:
**RANDOM VALUE FROM 1 TO 64 WITH AN ENTITY EXECUTING THE COMMAND**
EXAMPLE: We want to summon one of 3 mobs, called BOSS1,BOSS2 and BOSS3.
We want to choose the one that will be summoned with a random chance.
execute as @a[tag=canspawnbosses] at @s run function test:spawn_bosses
FUNCTION "test:spawn_bosses":
/function _random:3
execute if score @s random matches 1 run summon minecraft:zombie ~ ~ ~ {Tags:["BOSS1"]}
execute if score @s random matches 2 run summon minecraft:zombie ~ ~ ~ {Tags:["BOSS2"]}
execute if score @s random matches 3 run summon minecraft:zombie ~ ~ ~ {Tags:["BOSS3"]}

You can also use /function _random:17, /function _random:52 until /function _random:64
The random scoreboard is created when you call one of the functions.


**RANDOM VALUE FROM 1 TO 64 WITHOUT NEEDING AN EXECUTOR ENTITY**
/function _random:noentity/5
execute if score #server random matches 1 run say Option 1
execute if score #server random matches 2 run say Option 2
execute if score #server random matches 3 run say Option 3
execute if score #server random matches 4 run say Option 4
execute if score #server random matches 5 run say Option 5
The same of before, but it does not need a @s entity.


**RANDOM CHANCES with PREDICATES**
You should know how predicates work.
This datapack library also includes predicates for random chances from 1% to 99%
execute if predicate _random:32percent run function test:executed_with_a_chance_of_32_percent


**WHAT ARE THE LOOT TABLES FOR?**
That loot tables give you a random count of glass, from 1 to the value written in the loot table name.
TOTALLY USELESS, but NEEDED for the _random /functions to work.


Hope it helped you, by UltroGhast!