Adviser account activation requires that the national office already has your email account in their database and associated with your school chapter.
If you are already at an active chapter, and you are encountering an "Email address not found" issue when you try to activate your account, then you will need to contact the national office email@example.com to fix your account. (A known issue is that some advisers put their own email address on one or more student member registrations in the past. This causes a duplicate records issue that can be fixed, but only by contacting the national office to have it manually addressed in the system. This is a one-time issue/fix, thankfully.)
Students will be able to activate their accounts after they have been registered and paid as members and their adviser has input their email address in the registration process. Students need accounts to participate in BAA and other activities.