Since you need the content , not the format, consider buying an older edition (3–4 years old) from a second-hand bookshop or OLX/Quikr. Students often sell their atlases for ₹100–₹150 after clearing exams. Scan specific pages for your personal notes (fair use).
The physical Oxford Atlas is famous for its 15,000+ entry index. In a scanned PDF, you cannot search for "Chotanagpur Plateau" instantly. You have to scroll endlessly, wasting precious study time. Oxford Student Atlas For India Pdf Download -FREE-