• Create an Aura Component (or Lightning Component) named "TestLightningComponent" (or any other name of your choice) with the following code snippet - 
<aura:component implements="lightning:availableForFlowScreens,lightning:availableForFlowActions,force:appHostable,flexipage:availableForAllPageTypes,flexipage:availableForRecordHome,force:hasRecordId,forceCommunity:availableForAllPageTypes,force:lightningQuickAction" access="global" >
    <aura:attribute name="contactid" type="String" default="0032v00002pCaQB"/>  
    <aura:attribute name="param" type="String" default="&amp;isdtp=mn" /> 
    <aura:attribute name="iFrmURL" type="String" default="/apex/DragDropToCloud__DragDropUploader?id="/> 
    <iframe src="{!''+v.iFrmURL+v.contactid+v.param}" height="700px" width="1300px" style="border:0px"/>
  • Navigate to Setup -> Flows -> Click on New Flow button

  • Choose Screen Flow -> Next button.

  • Choose Freeform and the following page appears:

  • In the left panel of Flow Builder -> Drag Screen Element on Right Panel -> Drag above created Lightning Component into the screen

  • After all these steps, click Done.
  • Click the Save button and Activate the flow.
  • Click on Run and you'll see the following page: