Hey there,

I am really sorry for the delay of this reply as it is a weekend for us here.

It seems like I was unable to access your backend page, you can check my attached screenshot below.

Regarding your issue, you have to make sure your log/temp directory folder is set to writable permission (screenshot : http://take.ms/bhTfv )

After you updated your folder permission then try download the latest launcher installer from https://stackideas.com/dashboard then try upload through your Joomla backend installer page again and see how it goes.