The fantasy world is shared by two games (so far?). In the virtual mass multiplayer rpg, she played a "support" character, implying a healer.
Either the otome game is a spin-off of the mmo or they are both adaptations of a light novel. I feel a bit vague on the details.
From what I've read from the manga(untranslated), the main points are:
1) The MMORPG and the Otome Game share the same universe, by way of the Otome Game being an dev-approved spin-off of the primary game(For example, kind of like how "Phantasy Star Nova" was to base "Phantasy Star Online 2": Both games are linked to the main "Oracle Fleet" of PSO2, except that the characters in Nova are part of an expedition unit that's away from the fleet, and the main game's story happens back home with the main fleet), with the key difference being that the "Job Change" gimmick of the main game doesn't exist in the Otome Game, because, well, it's a re-playable Otome game, and the roles are fixed for the sake of the spin-off game's narrative.
The reason FMC knows that she can change jobs like in the main game is due to her finding the "Cat Robe" equipment, which is not part of the equipment catalog in the Otome game, and only exists in the main game(again: re-playable Otome game, which means limited content due to constrains with file size). This means that the job change gimmick ALSO exists here, it's just that no one in that world knows how to perform it, and pretty much everyone just automatically assumes that one is stuck with the class that they're born with.
2) While the FMC DOES indeed primarily mains a support class in the main game in her previous life, she wants to play as a healer so that she can one day shove it in the idiot prince's face for his rude remarks(because, while yes, despite having left the party with the moral high ground, she's still kinda pissed at the prince for breaking her heart, and trampling all over her efforts to become a worthy consort/queen).
Hell hath no fury like a woman scorned.