To a certain extent, some forearm pressure and pain is expected when you’re starting to work with kettlebells. Think about it like you’re playing volleyball. The impact might give a lot of pressure or even be painful sometimes. Trust your intuition to tell the difference between “ouch, this kettlebell flopped down harder than it should have” and “oof, I’m holding the bell correctly but it’s putting a lot of pressure on my forearm because it’s heavy.”
Just like with volleyball, you will likely have to go through some growing pains until your body builds up more muscle and improves technique enough to not get beat up with the weights as you rack them and perform the movement. Trust your body and listen to its signs — and never lift through sharp or shooting pains.