Tried to activate web player 3 on http://cogneon.de/mgmt20 - the player on the individual episode pages seems to work. But on the podcast landing page I get the following message:
Warning: Invalid argument supplied foreach() in [...]/player_v3/html5printer.php on line 53
I assume you generate http://cogneon.de/mgmt20/ using Podlove Templates? Then you should also generate the player with {{ episode.player }}. If I understand the situation correctly, the problem should occur no matter if you are using v2 or v3 of the player. Due do the way WordPress works, the shortcode doesn’t know which post/episode it is in.