I live in UK and It took me a few times to work this out but the following steps work perfectly for me now
Click on the reward link
Select change app password (this can be the same password as you already have)
I then click the install app link (this takes you to app store) open app
It will spin as loading you do not have to wait go straight to my and do all the tasks
Then come back to the pindiy task page now click APPLY
This will open a different page do not do anything as it will return to the previous page then the reward bar is complete and click reward
Works this way everything for me. I live in the uk