std::chrono::duration < rep, ratio> template parameter inquiry to establish own duration objects

Question

I have std::chrono::duration< Rep, Period >, and I understand that Rep is pertaining to what format you want the duration count to be transcribed in and Period is an std::ratio< n, d> where the numerator is the amount of seconds and the denominator is the amount to get a single unit. But as I'm looking over the internet, I find std::chrono::duration < int , std::ratio<60, 1>> minute ( 60 ); says

Expected parameter declarator [ missing_param ]

when I look at reference std::chrono::milliseconds has two properties, rep and period.

the exact code is

#include <string>            
                           
#include <chrono>            
#include <ratio>

class object {
    private:
              
        std::string location ;          
              
        std::chrono::milliseconds creation(30) ;

    protected:           
    public:              
};
   

when I put this in, std::chrono::milliseconds<int , std::ratio<1,1000>> creation; and an error likes this shoots out

Expected member name or ';'

now keeping in consideration that just making an instance of this with no params creates the error

In template: no member named 'value' in 'std::chrono::__is_duration'

code looks something similar to std::chrono::miliseconds creation;

I'm using Ale for VIM to get the errors, i believe ALE returns it's own variations of GNU CPP Compiler. I could be mistaken. Ale is a linter.