What are the major Contraints while developing large scale

Question

I want to get it know i am going to have a very large scale application in which there are multiple roles and many modules , and it is for multi culture as well , I am going to build the web based and android native app for it, what would be the best technology for web MVC or .NET core , what are the security contraints in need to have attention on, what whould be the structure of my application like for mobile i do not need to rework much . 

also tell me it is good to use angular for it but i an thinking that google is releasing new version after every three - four months so if i use angular 5/6 and after 6 month a new version of angular comes in that what happend ?

 

List all contraints and which architecture i need to use it is large scale Saas baed application .