Pi ft817 help please


Help please,
Just got a pi4 I need the lead from the pi to yaesu817 but unsure which one I need,can someone help ?do  I need a sound card for the pi relay am new to all this so baby steps and learning curve ahead and hoping to keep it cheap as chips,I did buy a ud04ya lead for pc and mac but failed at getting that working 
Am hoping to tx and rx using FLDIGI and other modes,please can anyone help andy uk 

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