Web version only free one?

I am just learning about sketchup and am very confused. I was told there’s a free version. But is the free version only on the web? What will it do? what will it not do? I tried to download what looked like a free version of 2017, but it wouldn’t work because apparently i don’t have the right graphics card, whatever that is. But when I tried 2016, I instead got a trial version of pro. How do I find out about this issue? There is no way to contact the company?? why isn’t there any clear information on the website about this?

The current free version of Sketchup is called Sketchup Free and it is a web based application which functions through a browser window. It does a lot, there are somethings it can’t do, really depends on what you want to model. Sketchup Make was the desktop free version which was discontinued in 2017, the 2017 version of Make is still available and still works fine, provided your graphics card is able to support it.

is there a 2016 version of Make? (free)
where can I find out what the different versions will do (in detail)?

The trial version of Pro that you got with 2016, will become the free version, after the trial.

See this discussion about Make for 2016:

https://forums.sketchup.com/t/sketchup-make-2016-download-links/37503

The main differences between Make and Pro are that Pro includes extra solid tools, and it has many more import and export formats that it can support.

Also, a Pro license is required for a user to use Sketchup for profit.

especially the valuable vector-based formats for exchanging data with other CAD systems resp. modelers etc.: