Citation Style Language plugin causing error 500 in OJS

Using OJS with PHP 7.3.13
When I activate the Citation Style Language plugin if i try to open an existing article from user interface i get an error 500 (independently of the plugin settings):
PHP Warning: Declaration of SubmissionKeywordEntryDAO::getByControlledVocabId($controlledVocabId, $rangeInfo = NULL) should be compatible with ControlledVocabEntryDAO::getByControlledVocabId($controlledVocabId, $rangeInfo = NULL, $filter = NULL) in /home/zpz1cjlqqyhx/public_html/ojstest/lib/pkp/classes/submission/ on line 20
PHP Fatal error: Trait ‘Seboettg\CiteProc\Style\InheritableNameAttributesTrait’ not found in /home/zpz1cjlqqyhx/public_html/ojstest/plugins/generic/citationStyleLanguage/lib/vendor/seboettg/citeproc-php/src/Seboettg/CiteProc/Root/Root.php on line 21

I read a lot of answers related to problems with this plugin in the forum but i cannot see/understand any solution.

Thank you for your help