The game is played in turns. Each player plays their full turn before it becomes the next player’s turn, and the order of play is always clockwise around the table.
The game ends when one player has completed the construction of their sixth Cathedral section. That player gets 3 as a reward and the end of the game is triggered. The other players will have one final turn before the game ends.
If you wish to play the Solitaire Mode, you can find the rules you will need in the Solitaire Mode rules category.