Hi there!
I have developed and operated 2 Shopify stores from scratch before, so I have lots of experience with adding and replacing liquid codes. I also know how every ‘.’ and ‘<‘ is crucial to the successful installation of the plugin.
The only part here that would require your input, is number ‘2-3’ in the installation instructions, as that requires you to decide where you want your recurring form to appear on the Cart page (I would be happy to alter it once for you, if you decide but then change your mind the next day).
Anyway, all the best with the website transfer!
Kind regards
Phil Jordan