Disk space: installation of LOW 4 alone gobbles up some 105 MB.
This amount can increase when ephemeris files are created and stored (if you want to). Each year’s worth of ephemeris data requires about 1 MB disk space.

RAM: LOW 4.1 has been written for modern day, memory-rich computers, as it claims quite a bit of RAM. When starting it up, and opening a data file, it consumes already 23 MB of RAM. After opening a file this will increase to 50 MB or more. When doing some serious work, it can easily go beyond 100 MB.
To be on the safe side therefore, your computer should have 512 MB of RAM, and preferably more.