The error indicates that the questionnaire tables already exist in your database. If you are installing, that means Moodle doesn't know that it was already installed. if you are sure that there is no data in the questionnaire tables that you want to keep, remove (or rename them) from your database before trying to install the questionnaire.
Questionnaire (plugin)
Moodle 3.9 error installing questionary plugin
This discussion has been locked so you can no longer reply to it.