The suggestion about OnlineTestURL was for someone else, who was getting a message about being offline. You shouldn’t need to change that setting.
If you want to try installing SketchUp 2023, to then make sure you are signed out from it, here is the disk image file to download:
https://download.sketchup.com/SketchUpPro-2023-1-341-117.dmg
Download that file and open it, and in the window you see you can drag the SketchUp 2023 folder into Applications. After it is copied you can eject the disk image, then go into the Applications folder, and into the SketchUp 2023 folder. Open SketchUp, and in the welcome screen look at the avatar in the upper right. If you click on that and see an option to Sign Out, do that, and afterwards you can quit SketchUp 2023.
Once you are sure that you’re signed out you should then be able to open SketchUp 2024, and sign in without seeing a message about too many activations.