for one don't type in all caps, that is considered to you YELLING!!!!!!!!

second i already responded to one of your many threads!!!!!!!

no need to have multiple threads on the same topic

edit: ok looks like the mods stepped in.

 

not sure what you mean screen beam. care to elaborate?

 

From the specs...
"Wi - Fi Miracast™ certified smartphones, Android 4.2 or higher"
https://www.screenbeam.com/products/screenbeam-mini2/

Check if your Samsung A21 actually supports that, also you may need to install a supporting app from the manufacturer.