ArchiCAD uses operating system fonts. Some default fonts vary between Windows and macOS. Make sure you are using a common font which is present on all workstations. The standard fonts are usually the most reliable: Arial, Times New Roman, etc. It is, however, possible to use custom fonts. Verify that these custom fonts are present on both systems and install where necessary. There are some fonts that are unique to either Windows or macOS. When one of these fonts is used, the missing font will show as bracketed on the other machine. The text will still appear but will be shown as Arial. Please see the image below as a reference.