Why I can't enable shared folders in VMWare?

The VM must be powered off, not suspended, to change that setting. Boot the VM, then do a proper shutdown inside the VM, you should then be able to change that setting.

I know this probably goes without saying, but have you done VM > Install VMware Tools from the VMware Workstation menu? VMware Workstation temporarily connects the virtual machine's first virtual CD-ROM drive to the ISO image file that contains the VMware Tools installer for your guest operating system and you are ready to begin the installation process.