Since June 2024, Temporary Transit (TT) vehicles have been officially exempt from the requirement to have a Crit'Air sticker to drive in all Low Emission Zones (ZFE) in France, including Paris. So there's no longer any need to go to the trouble of obtaining this sticker.
If you travel in another countries, it is your responsibility to check the restricted traffic areas and to comply with the regulations of the country you visited.