Desktop version:
Please log in to your account and click the portrait icon / My Profile section in the top right corner of the page, then choose "Your profile" from the drop-down menu. Your profile ID is listed on your profile page under your name and age.
Mobile version:
Please log in to your account and click the portrait icon in the lower right corner of the page. Then, go to the "View my profile" page. Your profile ID is listed on your profile picture under your name and age.