Installing WordPress on a subdomain of an existing online store

Is this possible?

Yes.

If yes what are the recommended steps to follow ?

The same way you install WordPress at the root domain:

1) Create your subdomain. How you do this depends on your hosting provider

2) Install WordPress. If your host has an auto-installer for WordPress (eg Softaculous, Fantastico, etc), use this but install to the subdomain you created and not the root. Alternatively, you may manually upload the WordPress files to your hosting account and install manually.

See detailed instructions here: https://developer.www.ads-software.com/advanced-administration/before-install/howto-install/

Follow @gappiah guide and make sure to install in subdomain directory.