Hey Leniu,
After playing your 50th move, it is necessary to Claim the draw using the Draw button underneath the Submit Move button. ('Offer Draw' changes text to 'Claim Draw' in such a situation.) I'm not sure if such a draw is now allowed (as there has been a capture).
In one of my tournament games I've made 50 consecutive moves with no pawn moves and no captures, and no "draw" button has appeared. On the 51st move my opponent captured the rook. If the rule is 51 moves then please update the "learn -> chess rules & basics" section, because it clearly says 50 moves there.
Any suggestions? I dont want to just lose the game, as I could've easily made a 51st move if I knew i had to, I just moved anywhere assuming that it will be a draw after I complete my 50th move. Help please!