You try to install it. You try to upload it to a web tool. You try to open it in FontForge. Nothing works. You need a TTF, but you have a TTC.
from fontTools.ttLib import TTCollection convert ttc font to ttf work
A valid .ttc file (e.g., SourceHanSans.ttc containing Regular, Bold, Light, Heavy). You try to install it
On Windows, you can extract individual TTF fonts from a TTC file without needing additional software. SourceHanSans.ttc containing Regular