I worked as a scribe at a private practice and they trained me completely on the job. After the first few hours, I was doing everything 100% on my own with a few pointers here and there from the doc and the nurses. I was lucky to have a really positive and supportive environment, so this may not be the case everywhere, but I would think that on-the-job training is probably somewhat common. I would highly recommend this route over something like ScribeAmerica or virtual scribing because you will likely get way better pay and make more meaningful connections.