Are you trying to log in through your iphone or ipad? Or trying to click through URL/links from an email message on your iphone?
If so, each time you do that, wikitree doesn't think you're logged in. It's annoying as all get-out, but has something to do with Apple's obnoxious (though still well beloved by me) IOS operating system.
My workaround: hold your finger down on the link in the email message on your iphone/ipad until a menu pops up. One of the options is Copy Link. Do so. THen bounce over to your web browser and paste the link into a window where you are ALREADY logged into wikitree. Then you won't have to log in again.