[Monster and animals spawn even when disabled]

I have monster spawning and animal spawning disabled but they still spawn and its really annoying since im trying to make a flat server and hundreds of slime spawn

[2 of my plugins are red when i do /pl, how to fix?]

deluxe menus and skbee but skbee is sometimes green and sometimes red and when its green i have a skript that does work and when its red my skript doessnt work so im pretty sure thats the problem but its almost never green.

[An unknown error occured appears when i try installing a plugin]

so when i try installing placeholder api it says an unkown error occured but when i try instaling other plugins it works. Some other plugins also make the "an uknown error occured" message pop up. It says that placeholderapi is compatible and that i can install it from minehuit (i dont have to dowload it from external website then put it in minehut) Please help!