Yes. If you don't have an account, you will be prompted to sign up for one. To speed things up, you can use the Fast Checkout option to purchase one product.
Using Fast Checkout will create an account if you don't already have one. Along with your payment info, you will need to enter your email, name and select the acknowledgement that you are creating an account.
Once the purchase is finalized, you will be presented with a Thank You page where you can download the files for that purchase right away.
Please note that this download page will expire.
The files you purchase will always be available to download on your My Library page and you will need to sign in to your ArtStation account to access them.