Hi colleenc1959, TTC is a collection of fonts saved in the TrueType (. TTF) format. InDesign will not be able to use TTF directly, TTC to TTF File Converter - Xojo Blog
Or use fonttools subset to split (example extracts font at index 0): convert ttc font to ttf work
The original TTC contained duplicate glyph tables for each font. Fix: After conversion, use a tool like TTF Auto Hint or pyftsubset (from FontTools) to subset the font: Hi colleenc1959, TTC is a collection of fonts