Just do your best, we know you are in a tough situation.
It's so hard to be prepared when starting out in this hobby. The upfront costs can be daunting enough just for a regular setup. And then we trust our LFS to provide healthy fish to get us started. Unfortunately, that is very rarely the case.
I strongly recommend getting a cheap 10g setup when you can along with some PVC fittings for your local big box store. I set up my first QT system for under $60 from Petco. I would also get the med's listed in this post. With Velvet and some bacterial infections there isn't time to save your fish if you don't already have everything you need.
https://www.reef2reef.com/threads/medications-to-keep-on-hand.213574/#post-2445601
Hopefully you can get these things in time to save the angel fish. I know I love my flame angel! Good luck and please ask as much as you need to see if we can help!