Stylus Pen not working in Photohop

Hi

I use an HP Envy x360 laptop with a touchscreen. I recently purchased a Digiroot stylus pen to use for drawing in PS. I had not used a pen previously, relying on my mouse. 

I am on the latest versions of both Windows 10 and V24.0 of PS. 

The pen works as a mouse on all applications, including PS, for selecting menu options, and I can draw in MS Paint for example, but I cannot draw in PS. 

Appreciate any help out there, thank-you.

Steve