If you have login issues, consider the following points:
If the following message appears, try logging in from a different wiki page:
Forbidden
You don't have permission to access this resource.
This happens if a page title contains special characters and you try to log in on that page. [(A period (.) or dash (-) seems to be okay in the page title.] This seems to be related to a known issue, CONFSERVER-11285, which says to avoid the following characters in page titles:
If you still can't log in, and you are sure you have an account, there may be a problem with your password.