unique_ptr in namespace std error

Using Arduino Programming Questions
#1

Hi, guys I am trying to use send my sensor data to firebase, and I am getting
unique_ptr’ in namespace ‘std’ does not name a type
virtual std::unique_ptr getPtr(const String& path);
^
error. Can someone please help me fix this error

#2

Can someone please help me fix this error

Without seeing your code? Doesn't seem likely.

#3