Only if you already own the base game on Steam. There is no legal free standalone download of version 1.45.
August 2022 Status: Official Stable Release (Superseded by newer versions, currently 1.50+) i--- Euro Truck Simulator 2 Version 1.45 Download
In the dropdown menu, look for temporary_1_45 - 1.45 for incompatible mods . Only if you already own the base game on Steam