You can split the file on your Mac by using the latest version of Excel because versions from 2003 and prior have a limitation on importing a CSV file. Obtain latest Excel version that is available for Mac, use the Open menu and add your file. Notice that if your file is larger in size, the time of importing differs a lot. After this process, select the range of the rows you want to import and use Export Selection and your file and repeat this step for how many files you want to have.