Help the cat get used to the scratching post
There are cats that just start using it immediately, while others continue to scratch furniture and sofas, ignoring it completely. There are various ways to encourage the cat to use the scratching post especially if you didn’t get it when the cat was small.
The cat is an inquisitive animal, its curiosity must be stimulated. One technique may be to scratch the scratching post, the cat may want to do the same. The scratching post needs to be in a strategic position. Move it until you find the perfect one.