Hello Guillermo,
You may have one of two issues.
1) Can't find the product.
Go to support.ca.com, Download Management and Search for Product "CA Service Management - Service Management" and you should get the Service Management 17.2 products come up. Depending on what you're licenced for, it may look something like this:
2) Don't have access to the product.
You can get to the above location, but you don't see products listed.
This would be because your user/site is not registered for this product - for whatever reason.
We can't help with this directly. You'll need to go to log a CA Support issue (there is a link at the bottom of that page) and you should have access to a Product called "CA SUPPORT PORTAL" or similar.
Thanks, Kyle_R.