Is anyone else having trouble accessing their Shopify ecommerce on iPad. This was running fine until

I cannot access shopify ecommerce on our iPad, we use this as our till . All was fine at the beginning of the week but have a message saying update required. When we press update app a message says 'Download an older version of this app? The current version requires iOS 14.0 or later, but you can download the last compatible version.

When I press the Download button the message just re appears.

we are using an iPad 12.5.5

Any HELP please

Julie