I´m not sure how I had to setup my Magento store for correct tax calculating:
Shop is in Austria
Can please some help me to set the correct settings?
Maybe you can take a look to the Taxes docs: https://docs.magento.com/m2/ce/user_guide/tax/taxes.html
In particular, you could check this section: https://docs.magento.com/m2/ce/user_guide/tax/tax-class.html