Move your data over from Lexware

Open Settings, section Connections, tab Move your data. The tab also holds the Lexware connection card (see the page on connecting Lexware).
Under Source choose what to bring over: Contacts (CSV), Open items (CSV), Original documents (ZIP of PDF and XML), Opening balances as a DATEV booking batch or a CSV per account, or Lexware account (connected API). The last one needs the Lexware connection from the card further down in the same tab first.
Set the Cutover date: from this day on the app does the bookkeeping, and older documents Lexware has already handed to DATEV.
For a file source, pick the file under File. Then choose Preview. Nothing is imported yet.
Check the preview: the counts, and one line per item that says what would happen. If columns landed in the wrong field, change the field for that column and choose Read again with this mapping. If the app asks which character separates the decimals, answer it.
When it looks right, choose Import. Finished runs are listed under Previous imports, and imported opening balances under Opening balances.
A payslip in a ZIP of originals is listed as not imported ("payslip cannot be attached to a booking"). Upload it through the receipt archive instead.