As you said it needs to be in Fasta format.
Here a complete programmatic solution to get all EST related to your species using conda and GAAS toolkit.
conda create -n gaas
conda activate gaas
conda install perl-bioperl
conda install perl-bio-eutilities
git clone https://github.com/NBISweden/GAAS
GAAS/annotation/Tools/NCBI/ncbi_get_reference_data.pl --db nucest --organism species_name