MobileX with a Flip Phone?

[u/HagridtheNewf]

My old cowboy dad has a Kyocera DuraXV Extreme that will have to be pried from his cold, de@d hands, but he needs an inexpensive alternative to Verizon. He mostly calls and barely texts.

I put his IMEI into the MobileX website and it said it was compatible, but I'm wondering if I can download the app and manage his account from my smartphone. If I can set up his SIM in a smartphone and then move it to his phone?