There is nothing to download, just sign in and use it.
Then you can use the Adobe PDF pack services.
You may also use some the feature of Adobe PDF pack in the Adobe Acrobat Reader application (desktop and mobile).
To install Adobe Acrobat Reader on Desktop, use this link Adobe - Adobe Acrobat Reader DC Distribution.
On mobile, you can install Reader from Google Play store in Android and App store in iOS devices.
Let us know if you need any help or have any questions.