Probably the easiest & quickest way to do this would be to use a low-code/no-code automation tool such as Integromat.
As far as I know, Integromat is the only automation tool that has deep Squarespace integration:
p.s. I am an Integromat Expert+ Partner and Airtable consultant. If you have a budget for your project and you’d like to hire someone to help you set this up, please feel free to contact me through my website: