My laptop crashed and I installed my 2020 (18) licence on a new laptop. Installation seems correct; the opening screen is as always. Entering one picture in a new project does immediately fill part of the screen with stripes.
This is usually the result of an outdated graphics driver. You don't say what operating system you're using but, if it's Windows, go to the Intel, nVidia or AMD site and download the latest driver for your graphics card and then reboot.