Yes, non-Word users can still upload their writing to Tablo.
Because Microsoft Word is a universal format, most word processors have an option to let you save your work in a Word document—including Google Docs and Pages.
Here's simple instructions for exporting to Word.
Google Docs
From your Google Docs document, click File > Download > Microsoft Word (.docx)
Your download will start immediately.
Pages
From your Pages document, click File > Export To > Word
Click Next
Enter a name for your document, then choose a location for the file.
Click Export.
Zoho Docs
From your Zoho Docs document, click File > Download As > Microsoft Word (.docx)
Your download will start immediately.