Some success , on the live server maria db it installed and seems to work.
on the local server mysql db it wouldn't update,so deleted everything and still wouldn't install,went to DB and removed al traces of engage and it installed.
Went to back end and did basic config,ok, went to frontend and made post ,ok went back to backend and...
D:\wamp64\www\j4\administrator\components\com_engage\src\View\Mixin\LoadAnyTemplate.php(99): Akeeba\Component\Engage\Administrator\View\Comments\HtmlView->loadTemplate('warning', false, Array)
#1 D:\wamp64\www\j4\administrator\components\com_engage\tmpl\comments\default.php(41): Akeeba\Component\Engage\Administrator\View\Comments\HtmlView->loadAnyTemplate('common/phpversi...', false, Array)
#2 D:\wamp64\www\j4\administrator\components\com_engage\src\View\Mixin\LoadAnyTemplate.php(224): include('D:\\wamp64\\www\\j...')
#3 D:\wamp64\www\j4\libraries\src\MVC\View\HtmlView.php(218): Akeeba\Component\Engage\Administrator\View\Comments\HtmlView->loadTemplate(NULL)
#4 D:\wamp64\www\j4\administrator\components\com_engage\src\View\Comments\HtmlView.php(140): Joomla\CMS\MVC\View\HtmlView->display(NULL)
#5 D:\wamp64\www\j4\libraries\src\MVC\Controller\BaseController.php(692): Akeeba\Component\Engage\Administrator\View\Comments\HtmlView->display()
#6 D:\wamp64\www\j4\administrator\components\com_engage\src\Controller\Mixin\ControllerEvents.php(74): Joomla\CMS\MVC\Controller\BaseController->display()
#7 D:\wamp64\www\j4\libraries\src\Dispatcher\ComponentDispatcher.php(146): Akeeba\Component\Engage\Administrator\Controller\CommentsController->execute('main')
#8 D:\wamp64\www\j4\administrator\components\com_engage\src\Dispatcher\Dispatcher.php(75): Joomla\CMS\Dispatcher\ComponentDispatcher->dispatch()
#9 D:\wamp64\www\j4\libraries\src\Component\ComponentHelper.php(389): Akeeba\Component\Engage\Administrator\Dispatcher\Dispatcher->dispatch()
#10 D:\wamp64\www\j4\libraries\src\Application\AdministratorApplication.php(143): Joomla\CMS\Component\ComponentHelper::renderComponent('com_engage')
#11 D:\wamp64\www\j4\libraries\src\Application\AdministratorApplication.php(186): Joomla\CMS\Application\AdministratorApplication->dispatch()
#12 D:\wamp64\www\j4\libraries\src\Application\CMSApplication.php(278): Joomla\CMS\Application\AdministratorApplication->doExecute()
#13 D:\wamp64\www\j4\administrator\includes\app.php(63): Joomla\CMS\Application\CMSApplication->execute()
#14 D:\wamp64\www\j4\administrator\index.php(32): require_once('D:\\wamp64\\www\\j...')
#15 {main}
I am not confident with live site to test there as yet. Thanks for your efforts Nicholas.
addendum: the live server test site is using Cassiopeia and it worked, Live site and local test site are using a Rockettheme template and they don't work,coincidence?