We have now opened a commercial services section here on the forum for registered users. If you have a Fabrik project that you wish to have someone work on for you, post it under Help Wanted. If you are an application developer and wish to earn some money helping others, post your details under Fabrik Application Developers.
Both of these are unmoderated. It will be up to both parties to work out the details and come to an agreement.
For running J!5.1 you must https://fabrikar.com/forums/index.php?wiki/update-from-github/ or include the new file manually https://fabrikar.com/forums/index.php?threads/joomla-5-1-and-fabrik-cannot-find-files-error.54473/post-285151 See also Announcements
Which Joomla template are you running? Did you try with the standard "Protostar"?A Joomla template that Supports the bootstrap framework
Memory limit is a good hint, but your system information is showing only 24M!! (System Information/Php Information, search for memory_limit)The memory limit is now 128Mb