Create a quotation
In order to change the status of the opportunity to sale, you must create a quote.
Create the quotation
Option 1 - using the quotation icon
Option 2 - using the green + plus sign in the right grey column
Enter the name of the quotation of your choice -> Choose the opportunity -> Choose the exchange if necessary and then -> click on Create
When the quotation is created, the color of the card and the column will change to blue
It is then that you will be able to change the status of the opportunity with all these choices: