OP:
Try this:
Download LibreOffice onto your Mac:
Download free office suite for Windows, macOS and Linux. Microsoft compatible, based on OpenOffice, and updated regularly.
www.libreoffice.org
It's free.
Put LibreOffice into your applications folder.
Next, move the file in question from the PC to the Mac.
Just leave it on the desktop so you can find it easily.
Now, open LibreOffice.
Click "open file".
Now, select the ".xlr" file, and see if Libre can open it.
Does this work...?
If it DOES work, you can now re-save the file either in Libre "native format", or use the "Save as" option and export it to another file format.