AFAIK, there is no other plugin strictly focused on SEO. However, the plugin seems to be working for me: I could install it, change settings and they seem to be reflecting in the site. Note the qa-ultimate-seo directory (which contains the qa-plugin.php file) needs to be a child of the qa-plugin directory.
You might need to clarify what exactly is not working.
EDIT:
Regarding this warning:
Warning: count(): Parameter must be an array or an object that implements Countable in /srv/users/serverpilot/apps/<HIDDEN>/public/qa-include/qa-base.php(725) : eval()'d code on line 160
You should follow these steps to fix it (not it is not an error but rather just a warning):
1. Locate this line
2. Change it to:
if(!empty($this->content['navigation']['cat']) && qa_opt('useo_cat_title_nav_enable')){
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