Thank you. Please try the following:
When you are available, please reply back to continue. Or you can try the next solution(s) below if the 1st solution above did not work:
1. Click on the Apple logo / menu, then click on System Preferences
2. Then click on Printers & Scanners
3. There, click on the Brother printer, then click on the - (minus) button at bottom left, and confirm to delete the printer for now. Make sure there is not any Brother item showing there for now.
4. Click on the Brother website below:
5. Open / run / install the download file Brother_PrinterDrivers_MonochromeLaser_1_2_0.dmg
6. Make sure the printer is powered on
7. Click on the Apple logo / menu, then click on System Preferences, then click on Printers & Scanners
8. Then click on the + (plus) button at bottom left, then select / add your Brother printer
9. Then check printing PDF files.
Please let me know. Thank you,