Q: Airport Time Capsule set up failing

Hello,

I have  property in Spain with the following equipment;

MacBook Pro 2013

Apple airport Time Capsule 2 TB

ISP Jazztel/Orange 50 MB fibre optic cable

Jazztel DSL cable modem

Jazztel supplied ZTE Router , Model ZXHN H218N

Unfortunately the setup for this combination of equipment appears to be non-standard so the "easy installation" is simply not happening for me. I would like to use the Apple airport as the main router if possible with wireless backup to the hard disk on the airport, but I would settle for using the airport to extend the existing wireless network and back up to the airport hard disk drive over existing wireless network.

1) does anyone have step-by-step installation instructions please?

2) is there a way to completely reset the airport unit and start over?

3) if the airport is incompatible with this network, is there away to directly back up to the airport HDD?

Many thanks,

Chris.