Possibly the holes in the side of the tube were worn into it from your tube/tire not being inflated enough and the tube got caught between the tire bead and tread as you rolled along. Pretty similar to a pinch flat.
When you get to the extremes of the recommended tire width to rim width, you have to expect that some tires on some rims might not do as well as others. There's no requirement that tire makers build their tire to conform with the commonly accepted size range we often see on charts. And quite a few tire makers lately seem loathe to provide their own guidance for rim width.
Also, what is the max width tire can I safely install on this rim?
Usually this is something you find out for yourself with your own experiences. If you've made certain you've kept the tire inflated enough and you still have this issue, then change the rim or the tire width. Same thing if you find the tire tends to roll under the rim from side to side making you feel unstable as you go down twisty turns.
And don't just go by the recommended tire pressure for your weight and size tire. Those are good for a first try, but you might need to go higher or lower. Again, you find this yourself by experimenting to see what works best for you.
Welcome to BF!