In order to get free rewards through Twitch Drops campaigns between Activision and the platform or to collect your Prime Gaming gifts, you have to link your Twitch and Activision accounts. To do this, you will have to follow the steps given below:
Create an Activision account or login to your account on the login page
Then go to Twitch and log in to your account. If you don't have one yet, create one
Once you are successfully logged into your two accounts, simply click this link
You will then end up with a new page as. On this page, click on the “Allow” button
In the Social Media section of the Profile page, click the "Link to Account" button next to Link to Twitch Account, then click Continue
There you go, your two accounts are now linked. Now all you have to do is follow one of the streams allowing you to obtain drops to collect your free rewards.