How can I find out PipelineDeals API key?

In order to get your PipelineDeals API key, you should log in your CRM account and go to ‘Account Settings':

pipelinedeals_account

After that, in the sidebar press 'PipelineDeals API' and enable API access:

enable_API_Pipeline_Deals

Right there you may copy your PipelineDeals API key and paste it to the corresponding field in the migration wizard:

api_key_pipelinedeals