Hi Mate, hope this helps because initially I was confused by it all.
Step 1: Set up your corners normally and don't worry about the second man attacking the far post for the moment. As you'll see from the screenshot below there are two players attacking the far post. However it would usually have the striker set with "go forward", this maybe different depending on your setup.
View attachment 686931Step 2: Now you've closed your set piece wizard and you'll see this screen
View attachment 686933 now you see on the left there is a tab labeled "stats" if you click it you get this drop down menu.
View attachment 686934What you want to select from that menu is "attacking corners" then your screen will look like this
View attachment 686936.
Step 3: Now you've got the above screen what you want to do is to un-tick the player with the "attack far post" option usually a defender so it looks like this
View attachment 686939. You're striker will still have "go forward" most likely so just change it using the menu by his name to "attack far post" like this
View attachment 686945Step 4: Now your striker has the instruction you want. Go back to the player you un-ticked the defender and tick him and change his instruction to attack far post and it should look like this
View attachment 686947. Now you've got your two players attacking the far post.Hope that helps, sorry it's a little messy but I hope you can follow it.