You can initiate the scanning process from the Mac itself since the printer is defaulted to PC. There are several methods to scan.
You can use Image Capture application to scan. Go to Applications folder and open Image Capture application. Image Capture will recognize the scanner and show in left column. Select the scanner (printer) and click Scan.
Method 2 :
Go to Applications folder and open Preview application. In Preview application, click on File menu and select Import from Scanner.
Method 3 :
Go to System Preferences and select Print and Scan or Printers and Scanners. Select your printer in left, click on Scan top on right top and click Open Scanner.
Go to Applications folder and look for Brother application like Control Center. Open it and it will allow you to scan
Note : If you are unable to scan with your Mac, then go to Apple > System Preferences > Printers and Scanners. Delete the printer from the list. Then click plus button and click Add Printer (don't add it under Nearby Printers). Then from the list, select your printer and make sure "Use" or "Software" is set to Brother software and not AirPrint or Secure AirPrint. This will add the printer with correct drivers. Then do the above methods to scan
If you have any difficulty on following the steps above, please let me know and I will continue to help you
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