Hi,
Thanks for your interest in Nicepage!
HTML files cannot be uploaded to WordPress. You should export your site from Nicepage as a WordPress theme (with or without the content), and upload it to WordPress. Here are the instructions:
https://nicepage.com/doc/66707/install-wordpress-theme-and-pages
https://nicepage.com/doc/67768/export-and-update-wp-theme-from-app
https://nicepage.com/doc/67690/export-and-update-wp-content-from-app
Let us know if you have further questions!
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Sincerely,
Paul C.
Nicepage Support Team
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