How to fix build error "maximum ps_5_0 sampler register index (16) exceeded"?

So I'm in the home stretch of a project for Oculus Go. I was able to build and view the app in the headset but recently I imported and used an asset (specifically the Meadow_Terrain_Demo.asset file in this package). Then I would get build errors relating to shader saying "maximum ps_5_0 sampler register index (16) exceeded".

Would anyone be able to help give a quick or easy fix while still using that asset? Or help me understand what the sampler register index is?

Thanks in advance!