Here is how I got the Sibilance CM plug-in, found by Trebor, described here:
https://www.musicradar.com/news/tech/free-vst-au-de-esser-toneboosters-sibalance-cm-632437
First, get the Feb 2016 issue of Computer Music magazine (CAD $2.24 for me). The links to the iOS store and Google Play are on this page, or just search those stores for it:
https://www.musicradar.com/news/tech/computer-music-stereo-science-issue-226-february-2016-632439
Here is the direct Google Play link, however note that this might just take you to the latest issue, so you might need to scroll down and go to back issues, and find issue 226, or Feb 2016:
Then go to the FileSilo page that hosts the plug-in, here:
https://www.filesilo.co.uk/software/sibalance-cm/
Click “UNLOCK CONTENT”. Step through the steps it takes you through, to register an account with FileSilo, click Unlock at least one more time, and then it will ask a question, like “What is the word after ‘tone’ in the headline on page 88?”. I got it wrong the first time since I bought the current issue by mistake, so it asked another, so they seem randomized.
The tricky part for me was getting the issue (make sure Feb 2016) which I’d bought on my Android to switch from continuous scroll into page mode so I could find the page it referred to. On Android that was by clicking the grey toggle button on the top right. Then once in normal page mode, swipe to the page it is asking about to find the word it wants.
Not that bad - once you know how to do it!