Thanks for sharing your file! It was as @thermokarst suspected: there are trailing blank cells on each line that are probably being created by the spreadsheet program you're using. Deleting those trailing cells should fix it.
Here's the first few lines in the file you sent me:
sample-id,absolute-file-path,direction ,,,
RC01_K,/Users/jcothern/desktop/TaborModule/CompressedData/RC01_K_S157_R1_001.fastq.gz,forward,,,
RC01_K,/Users/jcothern/desktop/TaborModule/CompressedData/RC01_K_S157_R2_001.fastq.gz,reverse,,,
RC28_K,/Users/jcothern/desktop/TaborModule/CompressedData/RC28_K_S98_R1_001.fastq.gz,forward,,,
RC28_K,/Users/jcothern/desktop/TaborModule/CompressedData/RC28_K_S98_R2_001.fastq.gz,reverse,,,
RC37_K,/Users/jcothern/desktop/TaborModule/CompressedData/RC37_K_S110_R1_001.fastq.gz,forward,,,
Those trailing commas can be removed, resulting in:
sample-id,absolute-file-path,direction
RC01_K,/Users/jcothern/desktop/TaborModule/CompressedData/RC01_K_S157_R1_001.fastq.gz,forward
RC01_K,/Users/jcothern/desktop/TaborModule/CompressedData/RC01_K_S157_R2_001.fastq.gz,reverse
RC28_K,/Users/jcothern/desktop/TaborModule/CompressedData/RC28_K_S98_R1_001.fastq.gz,forward
RC28_K,/Users/jcothern/desktop/TaborModule/CompressedData/RC28_K_S98_R2_001.fastq.gz,reverse
RC37_K,/Users/jcothern/desktop/TaborModule/CompressedData/RC37_K_S110_R1_001.fastq.gz,forward
Let us know how it goes!