Fresh ginger refers to fresh, raw and unprocessed ginger, emphasizing the word fresh. For example, the newly listed ginger you just bought in the market is fresh ginger. If it is left there for a week, it will not be fresh. If it is left there for a long time, it will not work.
If what you want in your prescription is fresh ginger, you can buy it on the same day and use it as fresh as possible.