"i know that Explorer license can not create data sources" - not true. Explorers can create data sources via the Web Edit function if they have been granted that permission.
What do you mean by "access Tableau Prep flow"? Nobody can "access" a published flow other than to see that it exists - is that what you mean?
Explorers can indeed run a prep flow, if they have sufficient rights. It would unusual for that to be the case, as only the owner of the flow (or an Administrator) can manually run it (just like extract refreshes), and usually the owner of the flow will be the person who published it from Prep Builder (a Creator license).
What are you trying to accomplish?