It seems that Ubilinux uses init.d for the services so after you set your environment for using systemctl you may have some problems. The tutorial you are following was tested on Yocto.
If you want to do this on Ubilinux I suggest you to create a service with init.d. This thread could help you with this: setting current_pinmux mode on boot
If this doesn’t work I suggest you to contact EmutexLabs for more information about this image you are using.