Adobe After Effects 2020 is no longer available as a direct public download from official Adobe sources, as they typically only support the current version and the two previous major releases. However, you can still access After Effects through a 7-day free trial of the latest version from Adobe. Official Ways to Get Older Versions
If you specifically need the 2020 version for system compatibility or legacy plugins, there are a few official avenues: After Effects 2020 (ver 17.5) download? - Adobe Community Adobe After Effects 2020 Free Download