User defined payment (Paypal) - can't change it from "get price from - None (Manual)" - need to use a calculation

If you want to pass calculation to PayPal payment field you will need to add Form Calculation widget to your form.

How to Perform Form Calculation Using a Widget

After that you will be able to change Get Price From inside of the PayPal payment field. 

How to Pass a Calculation to a Payment Field

Here is my demo form: https://form.jotformpro.com/71836246588974

Feel free to test it. 

Hope this will help. Let us know if you need further assistance. 

if I add a calc widget, my options are now manual and 'clickto24'...

Yes, clickto24 is the field name of the Form calculations widget:

And I see you already set it in the payment field:

Is that what you were looking for?

Or you need some additional adjustments?

Please let us know.

Thank you!