For one thing, Dante never read Homer.
Like most medieval Christians, Dante did not have direct access to the original Greek texts. Instead, they would've learnt of ancient Greek mythology through the works of later Roman poets, principally Virgil and Ovid, who inevitably added their own interpretation to the epics. Dante, moreover, seem not to have even read the Ilias Latina, a Latin version of the Illiad.
He seems to have been unfamiliar with Ilias latina, a Latin version of the Iliad, now thought to have been the work of the Iliad, now thought to have been the work of Baebius Italicus in the first century CE.
Barański, Zygmunt G., and Lino Pertile, eds. Dante in Context. Cambridge University Press, 2015.
Specifically, Virgil portrayed Ulysses as a deceitful manipulator, whereas the Greeks seems to have considered Odysseus' cunning and quick wits a virtue. Virgil's version is the one that Dante encounters in Hell.
That said, the specific story Dante's Ulisse tells of his fate appears to be original work.
Dante's apparently original reworking of the conclusion of Odysseus' story is well known. The disastrous last voyage of this voracious and restless intellect has been read as a metaphor for the "misguided philosophical Odyssey" of Dante's own experience just after the death of Beatrice.
Lamberton, Robert. Homer the Theologian: Neoplatonist allegorical reading and the growth of the epic tradition. University of California Press, 1989.