Ik have the latest version of Mindmanager for mac, but I cannot find the slide button. Is this feature only for for the windows version?
Yes, unfortunately it has been removed in the 10.5 upgrade for MindManager for Mac. See this blogpost (search for 'Slides'): https://www.mindjet.com/blog/2016/10/mindmanager-for-mac-version-10-5/
This is most disappointing. I don't use the Mac version but removing the ability to export slides seems to be an extraordinary and retrograde decision. I had hoped that the arbitrary removal of key features from MindManager with little warning and no real justification was a bad habit that would end with the transfer of ownership to Corel, but apparently not.