Sounds like you have most of the "skeleton" of the coop/run. You can make a door at least a couple ways:I've been thinking about that. They're just smooth poles that click together, like old vacuum cleaner extensions, if you know what those are.
1) use 2-3 or 2x2 lumber cut to about 5-6 feet long. Use lumber "straps". Just make sure you find the flexible ones. here's one, not sure if it's the one I used:
https://www.homedepot.com/p/Simpson...anized-Heavy-Strap-Tie-HRS8/100374841#overlay.
2) get the missing chain link hardware for a gate from home depot or other, if you can find it small enough to work. Basically gate hinge
3) pound t-posts to use as a frame for a door.
4) call some other company that sells similar kennel kits and see if you can buy the base "stands" that you use to snap together the base. Or maybe find some chain link fencing posts/rails that the connectors fit inside of??
If that is too much, I really like the idea of the hoop coop/run.