I wanted to download a family tree template but have failed.I tried downloading through the templates pages and selected Family Tree template, which took me to Source Forge and a downloaded .zip file but there was no .oxt file only an .htm. I followed a YouTube to download templates and saved a file download.htm, I changed the extension to .oxt and it ended up in my Extension Manager and did not work so I tried to remove it but it will not delete.My first problem is how do I get rid of this in Extension Manager?My second question is how can I download a family tree template successfully?

Please help.

I didn't find the right solution from the Internet.

References:-
https://forum.openoffice.org/en/forum/viewtopic.php?f=29&t=86129
2d Motion Graphic

Thanks!