If installing fonts doesn't help, the PDF may have broken font references . Here is a workaround using (not free, but 7-day trial works):
The CID font family includes several variants, denoted by F1, F2, F3, and F4. These variants differ in their design and usage: cid font f1 f2 f3 f4 free download link
They relate glyphs to defined "character collections" rather than just standard western names. If installing fonts doesn't help, the PDF may
In many cases, these placeholders map to standard system fonts: CIDFont+F1: Arial Bold Myriad Pro CIDFont+F2: Arial Regular If installing fonts doesn't help