How can this be accomplished smooth corner join ?

 From:  Matadem
11323.4 
Tnx
I tried it but I cannot get it to fillet...for some reason 1 time at 1mm max.
I tried sweep but it lowers the measurement of the shape and I need to use exact measurment.

attached is the og file.

Let me know what I am doing wrong.

Thank you!
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