Some old archives are password‑protected. Try common passwords: mcl , tamil , vaidehi , or www.tamilfonts.com . If none work, find a different source.
the file (if it's in a .zip or .rar) using a trusted tool.
However, the original MCL company is largely defunct. As a result, , and the fonts are widely treated as abandonware. That said:
"This font is a reconstruction," it said. "Vaidehi is made from scanned letters, prayers, shop signs, and the hand of a woman named Vaidehi, who wrote small notes for people in her village. We stitched her marks together. Use it. Tell stories. Credit the hands."
Alternatively, copy the file and paste it into C:\Windows\Fonts .