I am updating my computer from Apple to windows and trying to transfer my sketchup now I can’t log into my licence due to an authentication error help. all I have from Trimble is an email address for sketchup
First log out from your Apple version of SketchUp, or if you have a Classic license, remove it.
If you have a subscription license you log in to SketchUp, log in with the e-mail you have used previously on your Mac. If you have a Classic license you must locate your old serial number and activation code and use them to add your classic license to your new PC. @colin has often been able to help with lost license details.
Go to sketchup.com and try to sign in with the email address you use in the forum. If that works it should also work from inside SketchUp.
If you get any errors, show a picture of what the error looks like, and the page that you are on at the time.
You do have an older Classic license as well. SketchUp 2021 isn’t on our downloads page any more, you would need to find an installer from somewhere else, if you wanted to use 2021 on your new PC.