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I will help setup everything. Please note I do not offer support for drop shipping.
One of the support team members for the Google Shopping channel saw my feedback on the Shopify App website and got in touch with me.
It turns out there is an issue at their end where the app is not communicating properly with Google Merchant Centre.
The workaround given has resolved the issue and my products have now uploaded to the Google Merchant Centre and the create campaign button has been reactivated for Smart Shopping Campaign.