It should be in the View menu → Show Bookmarks Bar.
You can see all your bookmarks (and edit them) from the Bookmarks menu → Show Bookmarks. That is their editor.
If you have bookmarks imported from other browsers, they might be in a different subfolder. You can drag those into Orion’s bookmark toolbar if you want them available there.
If you didn’t import the bookmarks when you first started Orion, you can do so manually: Importing Data From Other Browsers | Kagi's Docs
It is a new browser, still in public beta, and yes, there will be some UI bugs here and there. It’s not something I would recommend for general everyday use yet, but in your specific case and the OP’s, I think it is a better choice than using a completely outdated browser that won’t support modern websites (like legacy Firefox ESR).
What we call a web “browser” (like Orion) is a UI wrapper around the underlying rendering engine (in this case Webkit), and it is that rendering engine that ultimately determines a particular site or web app will work correctly.
So even if Orion has some minor quirks, if you can get used to them, that should let you use modern websites with fewer issues because the underlying Webkit is the same (or very similar to) the latest Safari’s — which you otherwise wouldn’t be able to get without a new Mac and the latest macOS version.
So if you’re stuck on an old computer and old OS, this may be a good choice just because your options are otherwise limited. On a newer computer, no reason (yet) to use that over mainline, updated Firefox. On an older computer, Orion is one of the very few browsers you can still run that has a modern rendering engine, so it’s better than nothing. (And hopefully it’ll get better over time!)a
I don’t think that will work on older Macs:
Requires macOS 11.0 or later and a Mac with Apple M1 chip or later.
Too bad 
I think this is one of those situations where you just have to weigh multiple bad options and decide which is the least of all evils You’re stuck on an old browser and OS on an old computer, and more and more things will continue to break over time.
That’s just the sad reality of the tech world we live in, where most of these companies are heavily investor-driven and trying to optimize for profit, like any business. That sometimes means making sacrifices to their least profitable users, often those who are on older computers that take more work to support The web world moves fast, too fast I’d say, and people will only get increasingly left behind… sigh.
It’s annoying, for sure, but what can ya do? Maybe after the passport you can save enough money to get a new (used) M1 Mac Mini? You can find them for $300ish on eBay, which is still a lot of money, but it would be a huge, huge upgrade over your existing machine and buy you a few more years at least.