Reinstalling probably won't help with the error log. Did you transfer the files individually with FTP? That often results in missing or corrupted files.
Did you use your hosts install service to install MODX? That's often unreliable.
Try visiting the site with your browser in Private or Incognito mode to see if that helps.
Try transferring the files as described here: https://bobsguides.com/modx-upgrade-faq.html
, then run setup.
In ru site find decision. In settings PHP need change mbstring.func_overload=0 and modx work.