v1.7.0 donwload files does not contain changes for support PostgreSQL 13. Due to network security reasons we could not clone. Hence we download v1.7 zip file and do make & make install the library and we ended up with error :

"Makefile:50: *** PostgreSQL 9.3 to 12 is required to compile this extension. Stop.".

When we cloned repo, build was successfull.