That is just the way the Casava format expects the files to be named. You could replace SampleID with your sample name, and could get the barcode from your metadata, or I think probably just make something up, the import tool should rename the files to what you put here, and the sample names should already be associated from the upload step.
You just need to make sure that whatever you put matches this regular expression: r'.+_.+_L[0-9][0-9][0-9]_R[12]_001\.fastq\.gz', so that it can be validly stored in the Casava Format. You could use a regular expression checker(like Pythex, though their SSL certificate seems to be stale right now, so you may want to find a different one) to verify that what you would like to use will work before trying the import and spending all of the time on it.