I'm not expert in Linux, but after soooo long I finally found a way to install Adobe Photoshop 6 on Ubuntu 18.04 (Bionic Beaver). Why Adobe Photoshop 6? That's what I got.

Before we continue, I assume you already familiar on how to install application on Ubuntu. Also prepare lot of internet packet data, you'll need it.

1. Install Wine & winetricks

$ sudo apt-get update

$sudo apt-get install wine winetricks

2. Install depencencies for Adobe Photoshop 6

$ winetricks atmlib gdiplus msxml3 msxml6 vcrun2005 vcrun2005sp1 vcrun2008 ie6 fontsmooth-rgb gecko

3. Install Adobe Photoshop 6

$ cd /home/user/path/to/installer

$ wine Set-up.exe

From here and on, the installation process will be the same as when you install Adobe Photoshop 6 on Windows.

Enjoy!