Well, first of all, assuming you are referring to loans you made to others, who are repaying you over time, you should not have set them up as customers. Customers are subsidiary ledgers under Accounts receivable, entities to whom you send sales invoices.
Loans you are owed should be set up as asset accounts. If you have several of them, you probably want to use special accounts reporting to a custom control account. See https://www.manager.io/guides/10555. Initial disbursement of the loan principal would be debited to the special account via a payment. Principle coming in from the loan recipient would be entered as receipts credited to the same account. Interest on the loan would be split out in the receipt and credited to some income account.
You could then drill down from the Summary and export the listing for the special account involved. If necessary, you could manipulate the export in a spreadsheet to make something sophisticated to give to the loan recipient. Understand, however, that Manager is not a dedicated loan processing software program and does not offer features customized for that market niche.
Having said all that, would it be possible to treat loan recipients as customers? Yes, and the loan would be created like a refund with a payment or credit note. In that case, you could print a transaction-type customer statement, but it would only reflect the transactions against principal, not interest, because the interest would be posted to a different account.