This version of Unity is unsupported.
Removed in version 2018.4.36

ProceduralMaterial.cacheSize

Obsolete Built-in support for Substance Designer materials has been removed from Unity. To continue using Substance Designer materials, you will need to install Allegorithmic's external importer from the Asset Store. public ProceduralCacheSize cacheSize;

Description

Deprecated feature, no longer available