nintex workflow cloud or nintex workflow sharepoint

Nintex Workflow:

Nintex SharePoint Online license is required. 

Nintex uses Office 365 workflow engine (Microsoft announced to retire workflow engines starting Nov 1st 2020) at the backend, hence these Nintex workflows have to be re-engineered. The workflow functionality will not be available till transformation is completed.

Alternate Option:

Transform On-Prem Nintex Workflows to SharePoint Online Nintex Platform by site Owners. 

I hope the above information will help you to resolve the issue, in case of any queries/questions regarding the above mentioned information then please let me know. I would be more than happy to help you as well as resolves your issues, Thank you.