If you can't find the link to request to be added to the Trusted list, (as stated in the comment above) then you can send a PM to the Profile manager and ask to be placed on the Trusted list for that profile. But you must give them the email address that you used when you joined wikitree.
You will also need to join the trusted list for each person you want to help manage. If that requires several requests because those profiles are managed by different people, then you send however many requests you need to send.