TWAIN scanner driver is not compatible with Photoshop Elements 2018.
TWAIN is an interface to import images from devices such as a scanner. The Photoshop Elements TWAIN plug-in connects to compatible devices that are installed on your computer.
Photoshop Elements 2018 runs in 64-bit mode. Currently, not many manufacturers have released the 64-bit version of drivers for their scanners. So the drivers are not compatible with Photoshop Elements 2018.