Statements from FIO Bank are controlled by a so-called bookmark, which needs to be set directly in FIO — not in Flexi.
The first step is to set the bookmark to the start date from which you want to download statements. One option is to set the token bookmark directly in the FIO Bank application.
Another option is to use the FIO API at the following address, filled in with your details:
https://www.fio.cz/ib_api/rest/set-last-date/{Váš token}/{RRRR-MM-DD}/
The mask YYYY-MM-DD represents the date format for which you want to set the bookmark. You can obtain your token in the FIO Bank application. Enter your details without curly brackets:
https://www.fio.cz/ib_api/rest/set-last-date/11fm23fkma4/2019-11-30/
For more information, please refer to the FIO API documentation.