No application form on the Curator application page

Flagging is used to raise issues for curators to look at. Typically this involves flagging content, such as photos for copyright infringement, or taxa, such as a genus that needs a new species to be added. It looks like you have actually already added two such flags. If you want to become a curator to edit the taxonomy, then just find 3 more taxonomic issues to flag. You can do this from the taxon page by selecting Curation —> Flag for Curation.