Omaha The Third Round:

The third betting round starts again with the player left to the button, and bets and raises are limited to the upper limit of the stake structure ($10/$20 game, $20 would be the upper stake).

When we say the bets are limited to $20, it refers to: a Bet (single bet) of the value of $20, so when a user places “BET” then it is $20, “RAISE” would be $40 – includes one additional bet and a call on the previous bet placed by a player. Bets can be placed by playing any of the following options – 

 Bet, Call and Raise. Combinations of these options are available to the player depending on the action taken by the previous player. The first player placing the bet would get the Bet option (the player left to the Button).

After this the fifth community card is dealt out – this is known as the River.