If the provider is not part of the insurance company's network and your policy allows it, you can request a reimbursement through the insurance company's app.
Just take a photo of the invoice and, if it's a more specific examination or procedure, take a photo as well of the prescription and any medical reports you think it's relevant to add.
If the reimbursement is approved by the insurance company, you will receive the corresponding amount in your account associated with the policy, or by check to your address if you do not have your IBAN registered with the insurance company.