Ubuntu 18.04 installer not able to set up LVM

If you want all the available options to customize disk partitions, raid, etc, you should install Ubuntu using the Network Installer.

You can download it from here.

You need an active internet connection for this to work. When the installer reaches the point where it asks you what desktop to install, mark Ubuntu Desktop and select Continue if you want to install the normal desktop. Of course, you can mark any other Ubuntu flavor on that same menu and install that one if you like. (Xubuntu Desktop, Kubuntu Desktop, Lubuntu Desktop, etc)