All the invoices are automatically sent to your billing e-mail.
If subscription was applied to your account or account of your collaborator, which you have access to, invoices can be downloaded in Billing History:
On main page of Standuply account on the left side click on Team icon/ ⚙️ and choose Billing option:
2. Then choose owner of the subscription in a dropdown and click on "Billing History"
3. Choose any invoice and on the right side click on "three dots"
4. Download your invoice