On one of the lessons (3) the word matching is not accepting the last 2 letters. They are the only 2 left on the board so I'm not able to move on because it comes as incorrect. I'm currently learning Hindi
A lot of users seem to have this problem and I guess the team is still working on developing a solution. You can report the problem on here.
Hopefully, it will be fixed soon. Until then, a possible workaround might be to clear the problematic lessons by using Duolingo on your browser.