Variable font problem

I am korean and my co-worker use microsoft Windows.
and he has some problem.
we downloaded some korean Variable font.TTF they no have .OTF File…
anyway i have no problem because i use apple iMac…
but my co-worker use Windows… and it dosen’t work Variable option in Figma.
when he use other Varible font.OTF file he can see Varible option in Figma…
how to solve this problem…

even i converted TTF > OTF and gave my co-worker but … it dosen’t work…

Hey there, thank you for reaching out! Is your co-worker receiving a missing font warning? Missing fonts warnings will display with a yellow ‘A?’ Button.
If so, please review the help article below for instructions on how to resolve this issue:
Manage missing fonts.
Also is your co-worker using the Desktop Application or the Font Helper? As a first step, I would recommend trying to use the Desktop Application to see if that solves this issue.