It's hard to say if this will work, but it might. I could be wrong, but it looks like the bottom bracket has a wider diameter (35mm) than Bafang calls for (33.5 mm). There are shims available, but I'm not sure about that specific size. You can buy threaded shims if you're bottom bracket isn't threaded. It's hard to tell from the photo. You may also be able to fabricate something with some sheet metal. The other question involves that space for the motor itself. That's trickier, but it might work fine. It looks like you'd have extra space, but the whole thing is kind of unconventional. You'd basically be installing the motor upside-down. In a typical install the motor is in front of the bottom bracket, but that might not be a problem. Hard to say, but it looks like the motor housing would fit inside the cavity in your bike frame. I've attached some dimensions in case you don't already have them.
If you haven't already bought a motor, I suggest you contact these guys: https://www.electrifybike.com/
I have no connection with them other than being a happy customer. I bought my Bafang motor from them and they'll do a free 30 minute phone consultation with you. I found them to be enormously helpful, and they might be able to answer your questions about dimensions. I ran into a couple snags during the build and they were helpful before and after the sale. They sell motor kits and build e-bikes, and they're good people to do business with. They're really knowledgeable. If nothing else, their website is a great resource for all kinds of e-bike info.
Good luck with your build. Let us know how you make out.