Hi @Lisa_Crummett, sorry about the Linker Primer Sequence and Barcode confusion --- keemei was originally written for QIIME 1, which had those requirements. You can use keemei to validate QIIME 2 metadata files by selecting the following option:
QIIME 2 metadata files don't have the same kinds of column-specific requirements as QIIME 1 did - please take a look at this section of the Metadata tutorial for a complete list of the requirements for QIIME 2 metadata text files.
The TLDR here is you don't need the barcode or linker primer sequence columns, you are free to add whatever metadata makes the most sense to you! Thanks!