Check that you have sufficient disk space. The database will temporarily grow to about 20 Mbytes during the regression tests. You will also need about 3 Mbytes for the distribution tar file. To check for disk space, use df -k . Store it in your home directory.
Some platforms use flex.
If your system uses flex then make sure you have a good version. If the flex command is not found then you probably do not need it. If the version is 2.5.2 or 2.5.4 or greater then you are okay. If it is 2.5.3 or before 2.5.2 then you will have to upgrade flex. If you need flex and don't have it or have the wrong version, then you will be told so when you attempt to compile the program.