Unity 2020.3.3f1 works best with:
When installing, ensure you select these modules (especially for 2020.3.3f1): unity 2020.3.3f1 download
The release was a critical update within the LTS lifecycle. It arrived shortly after the official LTS launch, bringing crucial bug fixes and stability improvements to the initial 2020.3 rollout. For many developers, this was the "golden" build where the major bugs of the tech stream were ironed out, but the codebase hadn't yet drifted too far from the original release. Unity 2020
Instead of running the installer manually, do this: unity 2020.3.3f1 download
Unity 2020.3.3f1 uses .NET 4.x Equivalent. In Player Settings → Configuration → Scripting Runtime Version, set to “.NET 4.x Equivalent” (not .NET Standard 2.0 unless required by packages).