You have two different issues preventing access from the windows machines.
Store by reference files must be stored in a shared directory and all computers must have mounted/mapped to this directory with a file path that matches that of the path in the container. If you were to examine the filepath in the container field, you'd find that the path to the file contains "Filemac" for files inserted on your machine and "Filewin" for files inserted on a windows machine and this produces different filepaths even if you have mapped/mounted the enclosing directory in identical fashion on all machines.
I can see that there's a relative path also entered in the container fields that will point to the same folder as you have located your database file and this reference is not platform specific. Thus, you might try placing your files there and inserting from that folder, but you may have to share the enclosing directory and this opens up the possibility that users could directly access the database file through the shared directory instead of open remote. If this is needed, you risk potential damage to your datbase file should any user try to open the file directly instead of through Open Remote. If you are using Insert Picture, you get a different format to the data logging the filepath using ImageWin and ImageMac. I'm not sure the relative path option works for it, but you can test and see.
There are work arounds that you can also use if you want to stick with store by reference: You can define calculation fields that compute the needed platform specific filepath from the filepath stored in the container field. With this approach, you still insert the file or picture into a container field, but then use the calculation field to display the image or to provide access to the file. Such a calculation field would be set to return "container" as it's container type.
Web viewers can also be used to display inserted pictures using a calculation that extracts the filepath from the container field and some developers use a rather expensive 3rd party add on called SuperContainer to handle this issue and others.
If you want to see the actual file path inserted into a "by reference" container field, you can either use show Custom dialog or advanced's data viewer with GetAsText(table::containerField) or you can define a calculation field with Table::ContainerField as its sole calculation term with text specified as its return type.
THANK YOU!! Once I move the database onto a server, I'll get all my users access to it let them know that they may not open the database directly through that server.