Substance plugin for 3dsmax 2020

For 3ds Max 2020, grab it from Adobe's official page: https://www.adobe.com/products/substance3d/plugins/substance-in-3ds-max.html — the main download button only covers 2022+, but there's an "Older versions" link near the bottom that has the installer for 2018–2021, which covers your 2020 setup.

If an old pre-2.2.0 version is already installed, uninstall it first before putting the new one in.

Also, this breakdown of the best 3D texturing software might help.

which substance 3d?