Squarespace shop review and update

Who we are:
We are a company that specialise in producing activity resources for older people and people living with dementia. These resources assist activity organisers in providing meaningful recreation for care home residents and older hospital patients.

What we want:
We sell a newspaper via subscription, plus we also sell training and other products and need a checkout that integrates Paypal, credit card, BACS, direct debit payments. As well as having these payment options we also offer monthly, quarterly and annual payment options for subscriptions. Our website uses Squarespace, the accounting software we use is Xero and our database uses FileMaker 15 so being able to integrate these is vital. Our current system does not link in everything together.

We are looking to have someone review our current shop system and shop front on our website, recommend changes where/if necessary and then implement approved changes. The shop needs to be clear and simple, so ease of use for our customers is a priority.

Task 1) Review of current system and recommendations of changes.

Task 2) Once approved move forward implementing changes.

I have attached a schematic of our current system. We are not sure if this is still the best option for us.