To save your file as a PDF in Final Draft Cloud, you need to export the PDF to your Vault, where you can then download the PDF to your device.
When in your file, click the Final Draft menu in the top left, then File, and select Save PDF to Vault:
You'll be asked to select a Project to save it to, or you can just select Vault if you don't want to pick a project. Click Save. The PDF will be saved to your Vault, and you'll get a notification when it's saved.
Click the Final Draft menu and then go to Vault. Your PDF should be available under your recent files. Click the three dots next to the PDF file and click Download.
The PDF will then be downloaded to your device, most likely in your Downloads folder.
NOTE: Your PDF will always include your Title Page. If you're submitting your script to a contest, we recommend removing any identifying information from the Title Page or removing the Title Page with a PDF editor. The ability to omit the title page from a PDF will be coming to Final Draft Cloud in a future update.