I cannot activate the plugin. When I try there is no activate button to be found
Judging from the screenshots the plugin seems to be corrupted.
I'd recommend removing the bundled version of LayerSlider first and then isntall the new one from us that you can download from CodeCanyon. Your sliders will not be deleted in the process as they are stored in the database.
You can find installation instructions in our documentation on the following url: https://support.kreaturamedia.com/docs/layersliderwp/documentation.html#plugin-setup
Best Regards,Attila | Kreatura Support Team