"The mangoes are not ripe"
No. Break it down with STROVE:
Subject: haya-. Negative plural prefix for the Ji/Ma class, to which maembe belongs (sentence with just one mango would be embe halijaiva).
Tense: -ja-. Negative past perfect tense marker, "not yet".
(Relative and direct Object don't apply here)
Verb (+ End) -iva. Stem of kuiva, to ripen.