Honestly this is worse than a "design issue" of the button styles or "people not reading" here.

"Register to collect endorsements" does not explicitly say whose endorsements. It is possible to read this sentence as a (slightly odd) way to say "Register to have your endorsements collected".

"Collect" is a rather ambiguous verb, if I saw a button on a different website saying "register to collect favorites", I would understand that the website is building the collection, from my clicking on items... not that others will fav my profile.

"Register as a candidate to collect endorsements" would have been much clearer, whether the visitor read the preceding block of text or not.