You installed only the main font but not the symbol font. Ensure you installed the exact "KFGQPC Arabic Symbols 01" file, not the "KFGQPC Uthman Taha Naskh" regular font.
Remember: Always prioritize official or open-source channels. One corrupted font file can compromise your entire design project—or worse, your computer. KFGQPC Arabic Symbols 01 font Fonts Free Download
For designers and developers looking to incorporate this font into their workflow, the KFGQPC releases these fonts for public use to promote the correct dissemination of the Quran. You installed only the main font but not the symbol font