The iPhone 5S A1530 supports the following:
Model A1530*: UMTS/HSPA+/DC-HSDPA (850, 900, 1900, 2100 MHz); GSM/EDGE (850, 900, 1800, 1900 MHz); FDD-LTE (Bands 1, 2, 3, 5, 7, 8, 20); TD-LTE (Bands 38, 39, 40)
https://www.apple.com/iphone-5s/specs/
I googled it in about 15 seconds...
Anyways its perfect for Europe AND Asia but in the US Its not going to work great with LTE. It supports Band 2 LTE which T-Mobile is expanding on outside metro areas but you really need band 4 as well for proper HSPA+ and LTE. Did you buy from someone out of Europe or Asia? They likely don't understand the difference in LTE frequency bands anymore than you do...I would try and cancel.