I can appreciate your frustration but we need to step back a bit here and contextualise this...
Xerte Online Toolkits is a free and open source web application similar to other free and open source web applications like Moodle and Mahara and of course many others. Each of these have similar goals to empower teachers and learners but primarily they are online tools that need to first be installed and configured on a live web server by a server administrator. Once up and running anyone who is granted access to that installation can use the tool from anywhere via a web browser and internet connection. Typically educational organisations will have webservers already running where Xerte Online Toolkits can be installed, or can set one up and if there isn't the internal expertise or time to do so then there is consultancy support and/or external hosting available.
It just so happens that these applications can also be installed and configured on a local web server like xampp and this can be easy to do but you do need to ensure that whatever webserver you are using is running properly before trying to install Xerte. This local combination is mostly used by developers for testing and developing these tools and xampp for instance isn't meant for use on a live production server. Unfortunately on a Mac it can also be a bit more tricky because of permissions that need to be changed on particular folders.
My suggestion would be to remove your current xampp install and start again. Make sure xampp is working including Apache and MySql before even trying to install Xerte.
Or speak to your IT team and ask about a proper webserver installation because it's only that way that you get all the benefits of authoring from anywhere and sharing and collaboration that comes from a liver server rather than just a local server that nobody else can access.
By all means continue to post your questions and progress here but it's obviously holiday time for a lot of people so responses may not be very prompt.
Also the evidence is long established now about the benefits of Xerte and the number of organisations using it worldwide
xot.xerte.org.uk/play.php?template_id=2 so in many ways the first step for anyone should be to get that institutional install rather than trying it out locally first. Or sign up for a low cost external account via
www.learningapps.co.uk or
www.12change.eu/
HTH
Ron