Hi!
I searched a bit and couldn’t find any drivers beyond what you have already tried.
The only solution that came to my mind was to download a Windows 10 virtual machine and download an original Wacom driver for your tablet from there.
Here is a general guide on how to install a virtual machine with Windows 10 on your Mac:
1) Download virtualization software like virtualbox or VMware Fusion and install it on your Mac.
2) Download an ISO image of Windows 10 from the Microsoft website.
3) Launch the virtualization software and create a new virtual machine by following the instructions provided by the program.
4) When creating the virtual machine, select the Windows 10 ISO image as the boot disk.
5) Follow the instructions to complete the installation of Windows 10 on the virtual machine.
6) Once the installation is complete, launch the virtual machine and sign in to Windows 10.
7) Download and install the driver for your Wacom Intous 3 XL tablet from the Wacom website.
Please note that this is only a general guide and there may be additional steps or settings specific to your system. Also, make sure you have a valid license to use Windows 10 in your virtual machine. To get it you can buy it from the Microsoft website or an authorized reseller. Once you have purchased the license, you will receive a product key that you can use to activate your copy of Windows 10 during installation or later from Windows settings. Make sure you purchase a valid license for the version of Windows 10 that you intend to use in your virtual machine.
After creating and configuring the virtual machine with Windows 10, you can start it by opening the virtualization software you used (virtualbox or VMware Fusion) and selecting the virtual machine from the list of available virtual machines. Then, click the "Start" or "Run" button to start the virtual machine. Once started, you will see the Windows 10 Startup screen and you will be able to log in as you normally would on a computer with Windows 10 installed.
To exit the virtual machine with Windows 10, you can simply shut down Windows 10 as you normally would on a computer with Windows 10 installed. Alternatively, you can also use the virtualization software menu to stop or suspend the virtual machine. Make sure you save all your work before exiting the virtual machine.
You can download the driver for your Wacom Intous 3 XL tablet from the Wacom website at the driver page: https://www.wacom.com/it-it/support/product-support/drivers. Make sure you select the correct driver version for your operating system and tablet model.
I hope I helped you!