Instead of downloading, use Google Fonts CSS import:
@import url('https://fonts.googleapis.com/css2?family=Inter:opsz@14..32&display=swap');
body font-family: 'Inter', 'Ars Nova Regular', sans-serif;
Notice: Ars Nova is the fallback, but Inter is the primary.
To ensure your download works better than most:
Solution: You are likely using the TTF version at a small size in a low-resolution program. Switch to the OTF version and ensure your software’s anti-aliasing is set to "Smooth" or "Sharp."