Low Poly Displacement Forest Pack by Artem not showing up in the content browser.

Hi all,
II bought the “Low Poly Displacement Forest Pack” by Artem awhile ago and I installed it into a project but none of the content shows up in the content browser.
The files are there but UE4 does not seem to recognize them being there.
It’s the first time I’ve come across this issue.
Any help would be great.