Each country has its own regulations, and all licences are different, especially if yours was issued outside of Europe. As a general rule, your full licence must cover you to drive vehicles under 3.5T and cannot be a provisional licence. This, in most European countries, appears to be a Category B Licence but can be referred to differently elsewhere.
You must have checked that your licence allows you to drive in the countries you are planning to visit, in order to avoid any trouble with the law during your trip. If t is not compatible, please make sure to provide us with an international licence, along with your regular licence.
Some vehicles on the website that weigh more than 3,5T. Although specific insurance can be applied, you must have a valid category C licence (or one allowing you to drive vehicles > 3.5T), in order to hire such vehicles.