Rolup chatting app - can’t create an account..

trying to create an account in rollup chatting app it just sends me this message that the network is unstable so yeah for some reason that's what it says and I can't create a counter for so there you have it um yeah so if you know any any reasons behind this or maybe this app is just not available worldwide maybe I don't know I'm using Wi-Fi my Wi-Fi is pretty stable but and I'm receiving SMS code message but just can't proceed and can't create an account