You need to use Acrobat to edit your PDF. So, if the file is stored in your Acrobat.com account, download it, and then open it in Acrobat to edit.
To download a file, log in to your account at https://cloud.acrobat.com/files and select the file that you want to work on. Then, click Download at the top of the file list. Your file will download to the Downloads folder on your computer.