从ai cc2015升级到2017，是否免费？I want to update Illustrator CC 2015 to 2017, is it free？

You need to check with your IT department. If they licensed Creative Cloud for you, then you can download all apps.

Right now you only have Photoshop and Camera Raw, so they may have gotten you either the Photographers plan or the one software plan, and neither one includes Illustrator or any other application. That is probably why you are getting this message about Illustrator.

If you go to Options > Manage Accounts and know your log-in, you may be able to find out what Plan & Products you have.

I strongly suspect they did not purchase the full Creative Cloud license for you, but you will need to confirm it with IT, looking at your account, or talking to Adobe.