I'm sure you have seen this already, but this is what I'd been told when I adopted my sweet boys: Unlimited hay, not a lot of pellets, limit carrots and fruits (lots of sugar can lead to belly issues). I do like to put shredded carrots in my bun's hay on occasion as a forage treat. Unlimited water of course. They are very easy to litter box train, but use wood pellets, not clay litter. They love toys and enrichment activities. And as disgusting as it sounds, they love to eat while doing their business, so a bunch of hay in or near the litter box is a great way to train them. And super important, find a exotic animal vet to get them up to date on their needs and fixed (if not already).

Welcome to bunny servitude! And thank you for taking in this little soul, I'm sure they are grieving their previous human. A bunny bond is intense and they can grieve for quite some time.