Pointer variable of forward declared template class?

I have a class exactly as below.

But I get errors when declaring pointer var to my class. What's happening here? There are some similar questions here but I couldn't understand why my case is not working as the pointer is of the class itself.

code:

#include<iostream>

template <class T>
class A;

int main ()
{
    A* objA = NULL;
    objA = new A();
    
    objA->foo("some string");

    delete objA;
    objA = NULL;
    
    return 0;
}

template <class T>
class A
{
    void foo(T);
};

template <class T>
void A<T>::foo(T str)
{
    std::cout << str << "\n";
}