Upgrading Owl caroussel extension to PRO version

Hello !

We have previouly installed the free version of the "RESPONSIVE BANNER SLIDER AND OWL PRODUCT CAROUSELS". This morning we bought the pro version but I'm having issues upgrading.

Since we installed the free version via composer, our instalation folder is under \vendor\weltpixel with two subfolders called m2-weltpixel-backend and m2-weltpixel-owl-carousel-slider-theme-free.

I have tryed coipying the code into each folder from the Backend and OwlCarouselSlider. I also copied the folder MobileDetect into the same directory.

When I try to compile I keep getting this error:

Class WeltPixel\MobileDetect\Helper\Data does not exist
  Class WeltPixel\OwlCarouselSlider\Block\Slider\Products\Interceptor generation error: The requested class did not generate properly, bec
  ause the 'generated' directory permission is read-only. If --- after running the 'bin/magento setup:di:compile' CLI command when the 'ge
  nerated' directory permission is set to write --- the requested class did not generate properly, then you must add the generated class o
  bject to the signature of the related construct method, only.

What am I doing wrong?

Thanks !