It’s an role issue. The operator of the website has to give your profile the corresponding rights.
So just have a look in the contact details and write an email for example.

more info:
https://learnosm.org/en/coordination/tasking-manager3/
https://wiki.openstreetmap.org/wiki/OSM_Tasking_Manager
Maybe a start point: http://tasks.openstreetmap.in/