Low risk for normal use on quartz.
Why
Quartz is a nonporous countertop material, and the manufacturer approves this cleaner for nonporous countertops and sealed stone. The product is a general surfactant-based spray, with no stated abrasive or harsh solvent chemistry.
What to do
Use on the finished quartz surface as directed; wipe away after spraying. Avoid use on damaged or unsealed surfaces.
pH
Not stated
Relevant chemistry
Plant-derived cleaning agents, including glucoside surfactants; citric acid and fragrance/essential oils are listed. No numeric pH stated.