To add a bit more to this, my base command is: ./configure --enable-sky130-pdk. The --enable-sram-sky130 command gives me access to various RAM blocks which would be useful. The --prefix=/home/schippes is just if you want to specify where to install the pdk. Without it, where is the default installation dir? Therefore, if I run the command given by the open_pdk link for example, it will install the pdk in some default location and also the ram. I need to also tell the ./configure command where the sw pdk root library is?

As Stefan Schippers mentioned in the previous question, the default PDK installation directory is

/usr/local/share/pdk

. This location is the default, so you won't need to specify it again if you decide to install another PDK later using open_pdk.