To read this data, FlowJo must first transfer it to the local disk cache. You must ensure that there is enough free space on the disk where FlowJo's cache is kept in order to transfer this file. (The notification dialog tells you how much free space you need to have).

If you want to open this file, you will need to delete enough files from the disk to create the required space. The FlowJo cache is kept in the same directory as the application. Therefore, this is the disk that requires more free space. If you start deleting files to make space, remember that you can first delete all of the files in FlowJo's cache. Then keep deleting files until there is enough room on the disk to transfer the file you need.