Downloading updates

i’m using version 18.0.16975 64-bit when i open it i get an announcement of new version, pressing it gets me into trimble page with no update downloads to be found anywhere!!! HELP!!!

The announcement is for the latest release of version 2019, which is 2019.3.

If you are not going to upgrade from 2018, then I’d switch off the update notifications.
Window > Preferences > General


does this mean that updating to 2019 involves buying the new version?
Are there any updates available for my 2018?

There was only 1 release for SketchUp 2018.

Not if your maintenance and support contract was up to date.

You’d check your license …

It should tell you if you can upgrade for free or how much.