You don't need to download sra files, but you can use fastq-dump from the SRAtoolkit (as @genomax2 mentioned already).
If you have the toolkit installed, you just have to name the SRA file which you want to have. It will be downloaded as a fastq file.
e.g., in linux terminal:
For paired, use this:
fastq-dump --split-3 SRR2393592
The easiest way to install SRA toolkit is from brew package. Follow this link to first install brew and once that's done, simply run
brew install sratoolkit in terminal