Unfortunately you can’t - SampleData[SequencesWithQuality] (what you are referring to here as demux.qza) must have quality scores - the SampleData[Sequences] found in seqs.fna doesn’t have quality scores.
Check out this tutorial for guidance on importing and dereplicating these data. Then, you can take a look at this tutorial for guidance on how to identify and remove chimeric sequences.
What the next step is depends on what’s been done so far. Could you please describe what exactly these reads are and what has been done up to the point of you creating the .fna file? As a side note, if you have access to the original raw fastq files for this project, that would certainly be the preferred method in analyzing this in qiime2.
Basically this is data that was processed through QIIME1 in 2016, and I can’t find the original fasta files, just the seqs.fna.
I’ve imported that seqs.fna file, dereplicated it, and am now doing the closed-reference OTU picking through vsearch. I can’t seem to figure out how I would denoise (dada2/deblur) the data - or if I even need to.
I’ve tried skipping it and moving ahead in the Moving Pictures tutorial to the sequence alignment stage, but I run out of memory both using the mafft and a fragment insertion using