If you want the convenience of a digital file without breaking the law (or getting a virus), you have options.
Learners often prefer Daichi over the more famous Minna no Nihongo because: It uses and realistic scenarios. Nihongo Shokyu 1 Daichi Pdf
Unlike a physical index, a PDF allows you to search for a specific kanji or grammar point (e.g., "te-form" or "kara") immediately. This is a massive advantage for quick revision. If you want the convenience of a digital