Bummer, It looks like you're offline. You must be online to add or remove SketchUp licenses. Please try again next time you are online

I have lisence 2018 and I have 2 device.

Can not use the second device says “Bummer, It looks like you’re offline. You must be online to add or remove SketchUp licenses. Please try again next time you are online.”

Can anybody help?

It is a known issue with your old SketchUp version. Instructions in this thread: