Since CC2020 Adobe has stopped publishing public download links for installers. So the only way to get a genuine installer for CC2021 would be to contact support and ask. They would provide it if they have it available
To contact support follow the instructions given below
1. Go to https://helpx.adobe.com/contact.html?rghtup=autoOpen
2. Wait a bit on the page that opens up, it should automatically open a chat popup. If that does not happen then look for a call out/chat icon at the bottom right, click over it and the chat popup should open
3. In order to talk to a human type "AGENT" in the chat box
4. If you are not able to get to the chat window, then disable your adblockers, firewall, enable cookies/scripts on your browser. If it still fails then change your browser/machine/network.
P.S. Be mindful of answering anyone who sends you a private message. See the following for more information about scammers
https://tinyurl.com/y7cfrr7y
-Manan