They can be in any folder you like anywhere on your system (local drive or network drive).
You just have to tell Archicad to load that folder as a library with the Library manager - FILE menu > Libraries and objects > Library Manager.
You can then associate those texture files to your surface materials in the surface settings dialogue.
Barry.
One of the forum moderators.
Versions 6.5 to 27
Dell XPS- i7-6700 @ 3.4Ghz, 16GB ram, GeForce GTX 960 (2GB), Windows 10
Lenovo Thinkpad - i7-1270P 2.20 GHz, 32GB RAM, Nvidia T550, Windows 11