You can add one more image.

Setting a limit of one image upload per participant, when you go to the "create new photo" dialog, at the botton it shows:
"You can add one more image."

And after the message it shows highlighted in orange a message box with:
"The option becomes visible when it has been approved by an administrator. This may take a while."

This is a bit misleading for the user. I think the best would be if these two message boxes are hidden in the case the limit of photos to upload is set to 1.

There is already a ticket which should improve the usability when adding photos. I have added your feedback to the ticket and we will take it into account.

As soon as it is done, we will get back to you here. Thanks a lot!

Hi,
We made changes to the text to make this clearer to the user.
Kind regards
Philipp