Usually in traditional music playing is learned by ear.
In Austria from the beginning there ware different schools to learn to play.
Today mostly “Grifschrift” is a sort of tabulator and is used to write down the fingering. But there are also schools that use standard music notation. The use of Griffschrift does not limit the way how the fingers are used. So different types of playing stiles exist side by side.
In the past the thumb was not used a lot, but now some use the thumb as well for playing. “Michelbauer” notation.
Some online school in German language: online shool in German language