Embedding sound file won't play when converted to PDF (Adobe Acrobat Reader DC)

I’ve been trying to embed a sound file into my PDF, but unfortunately it won’t play when opening the PDF.
At first it asks whether the file is trusted, to which i approve. Then it informs me that the document requires Flash Player, which is not supported after december 2020.

To my knowledge, the error implies that its STILL supported.

The file is embedded into the document like this (Similar to enter link description here):

/includemedia[
width=0.4linewidth,
totalheight=0.225linewidth,
activate=pageopen,
addresource=addresource/optaget.mp3,
flashvars={source=optaget.mp3}
]{fbox{Click!}}{VPlayer.swf}end{frame}

It seems like adobe reader cannot play sound files using flash player anymore?