It would have been wise to check the hardware requirements before buying the ChromeBook.
There is a substantial difference between Pro and SketchUp Free. The pro version has more tools, more import/export options, the tools can be expanded with extensions, you get LayOut, and with the Pro Subscription, unlimited cloud storage and SketchUp Shop. You also wind up with a license that permits you to use it for commercial work which it sounds like you’ll need.
SketchUp Free has fewer tools, very limited import/export choices, no extensions, no LayOut, limited cloud storage and no license for commercial use.
For a hobbyist, SketchUp Free might be all that is needed but it clearly is not the right choice for you.
You’ll want to get a decent computer to run SketchUp. If you can return the ChromeBook, apply that money to that computer.