The password for ours was on a sticker next to the OneControl display. There is a second sticker on the base unit in case that one gets lost.
Are you able to contact the dealer? As a 2025 model, you must have JUST bought it. This sounds like something they ought to help you with. If you really want to find it yourself, it's usually not that hard. Heartland often puts these things in odd spots but it won't be in the ceiling or underbelly which are the only truly hard places to get into in a typical 5'er. Start in the kitchen, particularly by removing any bottom drawers. They love to attach things to the floor under those drawers (this is a common place to find slide-room controllers as well).
In your storage area, look very closely at any vertical wood or carpeted decorative panels, especially near your furnace/water services. If they're carpeted these will be hard to see (try a magnet) but these panels are invariably removable with very little effort. That's how they replace water pumps and leaking valves. Usually they're just screwed in place with 4-6 screws apiece, and pop right out if you remove them. There is almost certainly going to be an area behind one of them where all the "ugly stuff" like your DC converter/charger, OneControl base station, water pump, etc are located. Once you find it, you'll find all kinds of stuff, so if you're a handy owner/DIYer this is a good area to photograph for later reference if something else is failing.