I use desktop MacOS so the following may or may not apply to your MacBook.
Did you download the Intel version of Processing 4.3.1 (not Apple Silicon)?
Under the Finder menubar item ‘Go’ do you see a directory called ‘Library’? If not, hold the control or option key while the menu is dropped down to see if appears as shown below:
Open the Library directory and you should see a ‘Java’ folder.
Inside of the ‘Java’ folder there should be a folder called ‘JavaVirtualMachines’
Open it and you should see a copy of openjdk-x.x.x or something similar.
Another thing you can do is open Terminal (it’s normally in Utilities folder in Applications directory; icon looks like a video monitor) and type java -version at the prompt and see if your operating system already has it installed.
