Menu link with username in url – how to?

Hello!

I am buildning a social network with buddypress and i just installed Buddypress Media. It works great but i what a link in the menu that leads to the users media upload page. The url therefore needs to change depending on which user who is clicking the link. For example
https://mywebsite.com/members/%username%/media

I have tried the example but I cant make it work. Im using a custom menu, if that is of any help.

Greatfull for all answers!