How to open the gate in donkey kong 64?

I know donkey kong 64 is a really old game but it came back to me and I never beat it and it is really bothering me but anyway on the last level I cant get through the gate to get the key I can see it in the glass and everything I just cant open the gate how do I pass the level and open the gate

Hi,

In Hideout Helm?

First, assemble all necessary items. Climb the hill with Lanky. Blast the Pineapple Switch with Chunky. Shrink Tiny to enter the machine room. Pull the lever with DK Rocket. Diddy through the DK Stars. Punch the gates with Chunky.