Simply, to mean "have to" (or must), in esperanto you say "devi". "Havi" only means the idea of possession (materially or abstracly) as said by Pauchjo. For example to take the same words: "Ili havas laboron" means "They have (own) a job"

Can you never omit the second subject pronoun like this: "Ili devas labori ĉar bezonas monon."?

Wha?t exactly is the difference between labori and laboras?

Vekiĝu, vi devas fari monon. Jes.

why "ili havas labori, ĉar ili bezonas monon money" has a mistake, only because this course is in beta or because i have it terribly wrong.?

"Need" and "have to" are synonyms. Why does Esperanto have two words for this, when there are no nuances between them? It seems odd for a calculated language to have redundancies.

My first thought was "they have to work because they embezzle money." lol.