I can't post on a padlet
For most formats, the + icon is at the bottom right side. If you're not seeing this icon anywhere on the page, it's possible that you are accessing someone else's padlet and the owner of the page doesn't allow posting (*yet). There's not much you can do for now but it wouldn't hurt to ask the teacher/owner of the padlet permission to write on the padlet.
I am the owner of the Padlet
Check the account that you're logged into and see if the username matches the username on the URL. You might be logged from an account that is not recognized as the maker of the padlet
My students can't post on my Padlet
Posting might be disabled on the current padlet settings. To allow writing for contributors, click
SHARE >> Change Privacy >> Visitor Permissions - Can Write >> SAVE