UK users - browse to \\vulcan\Knowledge_Tree\Software Share\Solidworks
CZ users - browse to \\samba\Knowledge_tree_mirror\Software Share\Solidworks

Double-click setup.exe

Select Install on this computer and click Next

Leave default settings and click Next

Click Next on the "System Check Warnings" screen.

Select "Upgrade Solidworks 2021 to Solidworks 2023 SP3.0" and click Next.

You MUST select the Upgrade option or you will create a brand new Solidworks installation and have duplicate installs on your PC.

On the next screen, it will say you need to change the Toolbox settings with red text

Select "Change" next to the Toolbox/Hole Wizard Options.

Select "Use an existing Solidworks Toolbox".

Tick the "Upgrade a copy of your 2021 Toolbox data" box and click Back to Summary.

Check the settings look similar to below and click "Download and Install".
It will take some time to download and upgrade to the new version.