Searching it via Google (since it doesn't have its own search box that I can find :( ) indicates DrZhark has gone back and forth over the past few years as far as whether to even allow the mod to be used in modpacks, so you might have better luck asking about it in the Discord. I noticed the Custom Mob Spawner download link routes through AdFly :( so I wouldn't be surprised if you get denied modpack permission.
0
It has been a while since I've used Mo' Creatures, but it has its own forum here: https://www.mocreatures.org/forum
Searching it via Google (since it doesn't have its own search box that I can find :( ) indicates DrZhark has gone back and forth over the past few years as far as whether to even allow the mod to be used in modpacks, so you might have better luck asking about it in the Discord. I noticed the Custom Mob Spawner download link routes through AdFly :( so I wouldn't be surprised if you get denied modpack permission.