installing in a subdirectory

Yes.

And how can i do that.

Create your sub-directory and FTP the files into that directory and start the normal install process. So, instead of https://www.sample.com/ you can install it at https://www.sample.com/subdir/

This also means that your wp-admin section is below all that as well: https://www.sample.com/subdir/wp-admin/

Pretty easy to setup, just make sure to double check the install locations during the setup process and under wp-admin/ Options menu.