Custom Rig Keeps Sliding All Over the Map

Hello! So Im trying to make a Custom Rig for me and my teams game, Super Oofy 64! The issue is when we made the rig, it keeps sliding around the map, Here is a free model I made for it ( Please dont just get it and re-upload it nor use it for your game, It will be taken down )

https://www.roblox.com/library/7081693019/BrokenStarterCharacter

Are the legs colid on? That could be an issue, also a HRP is needed, Im not checking the model so if it has one then I dunno

Yes they are, The feet also have collision on. Also, can you explain to me what a HRP is?

HumanoidRootpart, It makes everything function