Here are the steps I have followed and it works perfectly fine for me:
Created an OSGi config with com.adobe.cq.wcm.core.components.internal.services.pdfviewer.PdfViewerCaConfig under /conf/we-retail/sling:configs path.
Added the clientId property (Tried with one that I have generated form Adobe as well. You can try using "28b07c6be4d544f188dc2f36e33b196b" id. Both worked for me). If the clientId is not authorized to use in your domain (in mycase it's localhost), you will get an error while rendering the PDF with an error message "This application domain (http://localhost:4502) is not authorized to use the provided PDF Embed API Client ID."
Added the sling:conf property on /content/we-retail/jcr:content node with a value of "/conf/we-retail"
Overlay the pdfviewer component from /apps/core/wcm/components/pdfviewer/v1/pdfviewer to /apps/weretail/components/content/pdfviewer and removed all the child nodes.
Added the sling:resourceSuperType property with value as core/wcm/components/pdfviewer/v1/pdfviewer
Updated the componentGroup to We.Retail from .core-wcm
Navigate to /apps/weretail/clientlibs/clientlib-base location and add core.wcm.components.pdfviewer.v1 as the embed property where the clientlib is loaded on the page. This will ensure the required CSS and JS files are loaded for the component.