I´ll try to explain as detailed as I can and hopefully we will be able to come up with a solution!
So I log in on the browser and it appears everything is fine since this is the message I get
"YoU MusT KeeP THIs pAgE opEn wHiLE you plaY Logout
Please note if your using a page refreshing addon this page now only needs to be reloaded once an hour
News Update Feb 2017
Check it out here"
Then I open the game and type the same username and password and this is the messages I get
"Connecting to front server..."
"Request accepted, sending login..."
"Incorrect username or password (5 failed attempts causes 15min ban)"