This question doesn't seem to let me answer. I know it's protected, but I have 101 rep.
Hi and welcome to the site.
This is a common question on all the sites. Site wide, one must earn 10 reputation on the specific site you wish to post an answer on. The 100 point association bonus doesn't count toward the rep needed to answer a protected question.
The question is addressed on Meta.SE:
Users with 10 or more reputation can answer a protected question. However, the +100 account association bonus is ignored for this check, so you must have earned 10 or more reputation on that specific site to answer a protected question.