I can certainly understand wanting to use PayPal to accept payments from Instagram. You can use a PayPal.me link to do this, if you provide the link on your Instagram post. You can create a PayPal.me link by going to www.paypal.me. There isn't any way to directly take payments from PayPal on Instagram, but you can always have people DM you there orders and then provide your PayPal email address for payment. You could also send invoices. You can learn more about that here, https://www.paypal.com/us/smarthelp/article/what-is-paypal-invoicing-and-how-does-it-work-ts2137.
