ETS2 is currently on a much newer version (likely 1.50+). Old versions miss out on years of new trucks, map reworks, and technical fixes.
Let’s address the elephant in the cabin. Searching for a "free full version" often leads to piracy. However, there are to obtain v1.35 for free, and one completely legitimate paid method that is worth every penny.
Released in 2019, version 1.35 was one of the biggest updates in ETS2 history. It introduced:
Massive expansions to Germany, and the addition of Sardinia.