Hi MarineC!
I know that you need to convert your file to QuickBooks Online. I'm here to help you.
The most possible reason why you're unable to restore your file using the QuickBooks Desktop Premier 2021 Trial version is due to the taxes. Currently, QuickBooks Desktop is designed for the United States, Canada, and United Kingdom only.
You can still convert your company file using a third-party migrator like Dataswitcher. You may check these articles for your reference:
You can also manually import the data to QuickBooks Online. You'll just need either a CSV, Google Sheets, and Excel file formats.
For more tips in using QuickBooks Online, visit this page: Help Articles.
I'll be here if you need more help. Take care!
