How do I limit the number of spawns that happen in a dimension. Currently I can get Abyssalcraft Zombies and Ghouls to spawn in the Beneath but it spawns hundreds and keep spawning. Obviously this is not what I'd want. How do I get this to work like normal spawning numbers.

Spawn:
[
{
"dimension": 10,
"mob": ["Creeper", "Skeleton", "Spider", "Bat", "Zombie", "Witch", "Enderman", "minecraft:zombie_villager", "Slime"],
"result": "deny"
},
{
"dimension": 10,
"mob": ["abyssalcraft:depthsghoul", "abyssalcraft:abyssalzombie"],
"block": "minecraft:stone",
"result": "allow"
},
{
"dimension": 10,
"mob": ["abyssalcraft:depthsghoul","abyssalcraft:abyssalzombie"],
"result": "deny"
}
]

Potential Spawn:

[
{
"dimension": 10,
"block": "minecraft:stone",
"mobs": [
{
"mob": "abyssalcraft:depthsghoul",
"weight": 3,
"groupcountmin": 0,
"groupcountmax": 1
},
{
"mob": "abyssalcraft:abyssalzombie",
"weight": 8,
"groupcountmin": 1,
"groupcountmax": 1
}
]
}
]

there examples in the documentation that show you what you are doing wrong

Not that I've seen. Care to point me to that specific documentation?