You can select what should be in the Order No. field on the created SuperFaktúra documents:
It will be shown here:
Order Number
It is the numbering that Shopify generates automatically.
For example 1234
Order ID
It is the ID that Shopify generates automatically. You can add PREFIX and SUFFIX, and between them, there is Order Number. Format: PREFIX + Order Number + SUFFIX
For example: BB1234HELLO
You can edit that within Shopify Admin » Settings » General » Order ID section
