Am I compensated for volunteering?

An organization is not obliged to give you compensation. The starting point is that as a volunteer, you mainly get satisfaction and appreciation from something other than material things.

Of course, this does not mean that you should be worse off financially: the organization can provide an expense allowance, for example for travel or other costs you incur.

Be sure to discuss this in advance with the organization, so that you know what to expect beforehand.