Nether portals is installed. I renamed the folder for "world_nether" to "World2_nether" to correspond with the mutiverse world i created called "World2"

Every time I try to go through the portal I get bounced back and it says
"That portal goes nowhere"

I assume you figured it out? You can't just rename the folder, you'll have to /mv import the World2_nether world, otherwise, it doesn't technically exist yet!