Unless you're booking our Script Proofing and Polishing service, we only accept script, pitch and treatment submissions in PDF format.
It's very easy to export your Final Draft file (.fdx) as a PDF.
Here's a link - https://www.reddit.com/r/Screenwriting/comments/93pfak/does_anybody_know_how_to_export_a_final_draft/
And another one - https://kb.finaldraft.com/s/article/How-can-I-include-or-exclude-the-title-page-when-I-save-my-script-to-PDF
If you're having trouble you can also easily reach out to Final Draft directly, here > https://www.finaldraft.com/support/