In order to access your invoices, go to the Backoffice module
Then on the Billing tab (Left column on your screen)
Then go to the Invoices tab at the top right of the interface
So there are all the invoices.
In red: Not paid
In green: Paid
It is possible to download your invoice in PDF format by clicking on
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Credit:
On the Credit tab:
So you have access to your assets