Hi,
That could mean, that the database tables might be missing, due to a bad installation or incorrect database user privileges. I recommend re-installing the plugin, using this method:
– First, wipe all plugin data, via the Maintenance menu
– Then installing via the plugin manager
After that, the tables should be present, if the database user has the proper privileges. If this does not work, then on your hosting provider, make sure to check that the database user has the priviliges to Create database table. If you use CPanel, then it should look something like this.