You may read Tripura Rahasya or Saundarya Lahari for philosophical appreciation via free PDF. However, never attempt the Nitya Puja or Homa sequences from a pirated Paddhati PDF.
If you are looking to download or read legally, searching for these specific authors yields the best results: sri vidya sadhana books pdf
In Tantra, knowledge without preparation is "leaked energy." Many who download advanced Kriya PDFs (like Nava Avarna Pujas ) and try to replicate them cause severe psychological imbalance. Why? Because the Yantra (diagram) is a transmitter. If you turn on a 1,000-watt radio without a ground wire, you burn the circuit. Your mind is the circuit. You may read Tripura Rahasya or Saundarya Lahari