Only way to do that is to query for it using CB Query Field then substitute in the query field. There's no substitutions available for adding up how much they donated.

Also can I place the Art. Num. from the invoice into the email as well?

What substitutions available should be listed under the Presentation tab or same tabs as email is configured if using CBSubs Mailer. Invoice fields typically are not available and have to also be queried for as the emails are more based off the plan and not so much the basket (which is basically also the invoice). We've a feature ticket to try and improve this though by adding more substitutions.

What information you can substitute in is listed on the Presentation tab of your plans under "Substitutions in Thank You messages and workflow Emails". You are limited to subscription information. There is no substitution for substituting in the amount the user has donated. For CBSubs Mailer what information is available for substitutions is listed under "Substitutions" directly under the email configuration.

If it's not listed there it can't be substituted in without querying for it. To query for it you need CB Query Field, create a query field, then query the database for whatever you need (usually grabbing information from their most recent basket is accurate enough). The below for example queries for the most recent invoice number for a user.

www.joomlapolis.com/forum/277-cb-paid-subscriptions-support/236506-sell-tickets-and-provide-unique-identifier?start=6#293607