Hi there,
Sorry that you're facing trouble installing the presets in Photoshop 2020.
Not sure if I understand correctly, could you please elaborate and provide some more? Are you looking to install a preset set? Are you getting any error message? See https://helpx.adobe.com/photoshop/kb/plug-ins-photoshop-troubleshooting.html
Also, check that you are using the latest version of Photoshop 2020.
Thanks,
Akash