The pin is located in the lower part of the screen right under the stage and is grayed out when not in use and blue when in use. You can also use P on the keyboard to activate it.
I believe you need to select the object you want to animate before the pin appears.
If that does not work it may signify that your version is faulty. Maybe you need to reset preferences.
I have to correct what I said earlier. The pin is there whether you choose something or not.
This is a screenshot of the normal stage and the pin is showing - this is version 2014.1
The pin appear grey when it is not select and blue when it is selected. Pressing P selects it.
I suggested you try and reinstall Animate or see if you can install version 2014.1 or 2015.
thank you for your reply. Unfortunately, i have tried to uninstall and install the previous versions but it always redirects me to a page saying something like "From November 5th 2015, the older version will no longer be released," so I cannot download the older versions and am stuck with the newer (2017) version. So, am i right to assume that the toggle pin tool as well as other functions are no longer available in the 2017 version?
I think your problem come from the fact that "Edge animate CC" and "Animate CC" are two totally different apps. Animate CC is the new Flash, and Edge Animate CC is a (unfortunately) discontinued app to create animation in Html.
To download Edge animate CC you need to go to your creative cloud desktop App>Past versions>edge animate cc 2015
Hope it can help.