You can create a draft study. But in order to see what it looks like
from the participant’s perspective I think you would need to add
some money to your account. But, on reflection there is no need to
actually pay anyone the money.
If you tell us the external platform then perhaps someone knows
whether it is Prolific compatible or not. Since it is not necessary
to pass parameters from Prolific (you can just ask participants to
copy their ID over the external survey site) then all the survey
site needs to be able to do is show a URL for participants to click
at the end of the survey. Few sites can’t do this. Google forms, which is
free for non-business use, can do it without issue.
Got it! You could create a survey, publish it at the minimum rate with money in your account, white list only your own participant prolific ID (you will need to create a participant account with a different email address) and then using your participant account click through to the study and check it out, but “return” it rather than complete the study when, as a participant, you are should you could have pressed the completion link.