I have Joomla 4 and upon installing I get a Class J error - Can't find XML Setup file

What exact version of Joomla (4.4.0?) and Mobile (3.2.2?) are you trying to install? I've just tested the installation on a test website, and it works fine.

I have Joomla 4.3.2 and I bought Mobile Joomla Basic 2.1.54.

I see. Mobile Joomla 2.x is an older version of the Mobile extension that only supports Joomla 1.5-3.10. Currently we release updates to the local device database and going to fix only critical issues (if such will be found).

Joomla 4+ (including Joomla 5) is supported by Mobile 3.x only. In 3.x we split our extension into several packages, and full modern analog of Mobile Joomla Basic 2.x consists of following packages:

1) Mobile 3.x package www.mobilejoomla.com/download-mobile-joomla.html (Free),
2) Mobile Adaptive 3.x package www.mobilejoomla.com/extension/get/mobile-adaptive.html (Free),
3) Mobile Basic 3.x template www.mobilejoomla.com/extension/templates/basic-v3.html (free ad-supported or ad-free with purchased license),

Just install them in the specified order and select Mobile_Basic template to be used for mobile devices in the Mobile settings page.

Thank you all has been solved.. Thumbs up!!!!