to sign up, to enroll, to join
Quienquiera puede apuntarse.
Anyone can sign up.
Si quiere apuntarse.
If you want to sign up.
— State and Main (2000)
Aquellos que quieran apuntarse, que lo hagan.
Those who want to sign up, do so.
Todo el que quiera puede apuntarse.
Anyone who wants to can sign up.