HTML5 Export only by download viewable

When I export the mindmap to html5 it is working for me. When I am sharing it for colleagues over sharepoint, it is causing an issue...

A colleague is clicking on the link which is opening in a browser (safari, chrome, etc all the same issue). However they can not see the mindmap direcly, they need to click on download and then open the downloaded html file.

How can I solve this that everyone can open the link directly without a download?

Note: I have the latest Mac version of Mindmanager, but the other useres are on a Mac or WIndows, no difference.